- Mechanochemical Prebiotic Peptide Bond Formation**
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The presence of amino acids on the prebiotic Earth, either stemming from endogenous chemical routes or delivered by meteorites, is consensually accepted. Prebiotically plausible pathways to peptides from inactivated amino acids are still unclear as most oligomerization approaches rely on thermodynamically disfavored reactions in solution. Now, a combination of prebiotically plausible minerals and mechanochemical activation enables the oligomerization of glycine at ambient temperature in the absence of water. Raising the reaction temperature increases the degree of oligomerization concomitantly with the formation of a commonly unwanted cyclic glycine dimer (DKP). However, DKP is a productive intermediate in the mechanochemical oligomerization of glycine. The findings of this research show that mechanochemical peptide bond formation is a dynamic process that provides alternative routes towards oligopeptides and establishes new synthetic approaches for prebiotic chemistry.
- Cindro, Nikola,Grube?i?, Sa?a,Hernández, José G.,Me?trovi?, Ernest,Stolar, Tomislav,U?arevi?, Krunoslav
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supporting information
p. 12727 - 12731
(2021/05/07)
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- A dynamic combinatorial library for biomimetic recognition of dipeptides in water
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Small peptides are involved in countless biological processes. Hence selective binding motifs for peptides can be powerful tools for labeling or inhibition. Finding those binding motifs, especially in water which competes for intermolecular H-bonds, poses an enormous challenge. A dynamic combinatorial library can be a powerful method to overcome this issue. We previously reported artificial receptors emerging form a dynamic combinatorial library of peptide building blocks. In this study we aimed to broaden this scope towards recognition of small peptides. Employing CXC peptide building blocks, we found that cyclic dimers of oxidized CFC bind to the aromatic peptides FF and YY (K ≈ 229-702 M-1), while AA binds significantly weaker (K ≈ 65-71 M-1).
- Klepel, Florian,Ravoo, Bart Jan
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supporting information
p. 1588 - 1595
(2020/09/16)
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- Effect of high hydrostatic pressure on prebiotic peptide synthesis
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Prebiotic peptide synthesis is a central issue concerning life's origins. Many studies considered that life might come from Hadean deep-sea environment, that is, under high hydrostatic pressure conditions. However, the properties of prebiotic peptide formation under high hydrostatic pressure conditions have seldom been mentioned. Here we report that the yields of dipeptides increase with raised pressures. Significantly, effect of pressure on the formation of dipeptide was obvious at relatively low temperature. Considering that the deep sea is of high hydrostatic pressure, the pressure may serve as one of the key factors in prebiotic peptide synthesis in the Hadean deep-sea environment. The high hydrostatic pressure should be considered as one of the significant factors in studying the origin of life.
- Ying, Jianxi,Chen, Peng,Wu, Yile,Yang, Xu,Yan, Kaili,Xu, Pengxiang,Zhao, Yufen
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supporting information
p. 367 - 370
(2018/06/18)
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- Rapid, effective deprotection of tert-butoxycarbonyl (Boc) amino acids and peptides at high temperatures using a thermally stable ionic liquid
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A method for high temperature Boc deprotection of amino acids and peptides in a phosphonium ionic liquid is described. The ionic liquid had low viscosity, high thermal stability and demonstrated a beneficial effect. The study extended the possibility for extraction of water soluble polar organic molecules using ionic liquids. Trace water significantly improved product purity and yield, while only 2 equiv. TFA led to deprotection within 10 min. The trityl group was also deprotected.
- Bhawal, Sumit S.,Patil, Rahul A.,Armstrong, Daniel W.
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p. 95854 - 95856
(2015/11/24)
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- Coupling-Reagent-Free Synthesis of Dipeptides and Tripeptides Using Amino Acid Ionic Liquids
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A general method for the synthesis of dipeptides has been developed, which does not require any coupling reagents. This method is based on the reaction of readily available HCl salts of amino acid methyl esters with tetrabutylphosphonium amino acid ionic liquids. The isolation procedure of stepwise treatment with AcOH is easy to carry out. The method was extended to the synthesis of tripeptide, tyrosyl-glycyl-glycine, present in IMREG-1, also.
- Furukawa, Shinya,Fukuyama, Takahide,Matsui, Akihiro,Kuratsu, Mai,Nakaya, Ryotaro,Ineyama, Takashi,Ueda, Hiroshi,Ryu, Ilhyong
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supporting information
p. 11980 - 11983
(2015/08/18)
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- Pressure-induced oligomerization of alanine at 25 °C
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Pressure-induced oligomerization was found from high-pressure experiments at 25 °C on alanine powder soaked in its saturated aqueous solution. The oligomerization to alanylalanine occurred at 5 GPa. The maximum yields of alanylalanine and trialanine were, respectively, 1.1 × 10-3 and 1.3 × 10-4 at 11 GPa.
- Fujimoto, Chikako,Shinozaki, Ayako,Mimura, Koichi,Nishida, Tamihito,Gotou, Hirotada,Komatsu, Kazuki,Kagi, Hiroyuki
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p. 13358 - 13361
(2015/08/24)
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- Epimerization of cyclic alanyl-alanine in basic solutions
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Alanine anhydrides (Cyclo-(Ala-Ala)) are the simplest dipeptides that have two chiral centers and three diastereomers: Cyclo-(L-Ala-L-Ala), Cyclo-(D-Ala-D-Ala), and Cyclo-(L-Ala-D-Ala). Analysis of the epimerization of these peptides may throw light on the development of homochirality in proteins. We show that the epimerization rate of Cyclo-(L-Ala-L-Ala) and Cyclo-(D-Ala-D-Ala) is higher than that of Cyclo-(L-Ala-D-Ala), while the ring-opening rates of Cyclo-(L-Ala-L-Ala) and Cyclo-(D-Ala-D-Ala) arelower than that of Cyclo-(L-Ala-D-Ala) in basic aqueous solutions. The total reaction resulted in the preferred stability of Cyclo-(L-Ala-L-Ala) and Cyclo-(D-Ala-D-Ala) to Cyclo-(D-Ala-L-Ala).
- Munegumi, Toratane,Fujimoto, Takeshi,Michiotakada,Nozominagashima
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- The dimethylsulfoxonium methylide as unique reagent for the simultaneous deprotection of amino and carboxyl function of N-Fmoc-α-amino acid and N-Fmoc-peptide esters
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The dimethylsulfoxonium methylide is described as a unique and useful reagent for the simultaneous deprotection of amino and carboxyl function of N-Fmoc-α-amino acid and N-Fmoc-peptide esters. The new methodology was applied successfully both to solution- and solid-phase peptide synthesis. The adopted methodology was extended successfully also to peptides containing amino acids bearing acid-sensitive protecting group in side chains. Furthermore no measurable epimerization was observed in the deprotection reaction of N-Fmoc-dipeptide methyl esters with dimethylsulfoxonium methylide.
- Spinella, Mariagiovanna,De Marco, Rosaria,Belsito, Emilia L.,Leggio, Antonella,Liguori, Angelo
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p. 2010 - 2016
(2013/03/13)
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- Oligomerization of glycine and alanine on metal(II) octacynaomolybdate(IV): Role of double metal cyanides in prebiotic chemistry
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Condensation reactions of amino acid (glycine and alanine) on the surface of metal(II) octacyanomolybdate( IV) (MOCMo) complexes are investigated using highperformance liquid chromatography (HPLC) and electron spray ionizations-mass spectroscopy (ESI-MS). The series of MOCMo have been synthesized and the effect of outer sphere metal ions present in the MOCMo on the oligomerization of glycine and alanine at different temperature and time found out. Formation of peptides was observed to start after 7 days at 60°C. Maximum yield of peptides was found after 35 days at 90°C. It has been found that zinc(II) octacyanomolybdate( IV) and cobalt(II) were the most effective metal cations present in outer sphere of the MOCMo for the production of high yield of oligomerized products. Surface area of MOCMo seems to play dominating parameter for the oligomerization of alanine and glycine. The results of the present study reveal the role of MOCMo in chemical evolution for the oligomerization of biomolecules. Springer-Verlag 2012.
- Kumar, Anand,Kamaluddin
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p. 2417 - 2429
(2013/03/28)
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- Process For Producing Dipeptides or Dipeptide Derivatives
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The present invention provides a process for producing a dipeptide or a dipeptide derivative by using a protein having the activity to form the dipeptide or dipeptide derivative from one or more kinds of amino acids or amino acid derivatives, or a culture of cells having the ability to produce the protein or a treated matter of the culture as a enzyme source, which comprise; allowing the enzyme source, one or more kinds of amino acids or amino acid derivatives and ATP to be present in an aqueous medium; allowing the dipeptide or dipeptide derivative to form and accumulate in the medium; and recovering the dipeptide or dipeptide derivative from the medium.
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- Mechanism study on the oligomerization of amino acids into peptides by phosphorus trichloride
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As treated by phosphorus trichloride, amino acids could oligomerize into polypeptides. Based on the results obtained by 31P-NMR and ESI-MS/MS, a possible reaction mechanism was proposed. The mechanism might undergo a penta-coordinated phosphorus intermediat. The activated amino acid was a five-membered cyclic penta-coordinated phosphorus intermediate. The nucleophilic attack of the amino group from an amino acid or peptide on the carbonyl group of intermediate led to the formation of peptide and released one equivalent dichloride phosphoric acid. The repetition of the reaction sequence generated a series of oligopeptides. Copyright Taylor & Francis Group, LLC.
- Zhao, Wenjie,Zhao, Dongxin,Lu, Kui
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scheme or table
p. 691 - 698
(2009/05/07)
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- Direct asymmetric intermolecular aldol reactions catalyzed by amino acids and small peptides
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In nature there are at least nineteen different acyclic amino acids that act as the building blocks of poly-peptides and proteins with different functions. Here we report that α-amino acids, β-amino acids, and chiral amines containing primary amine functions catalyze direct asymmetric intermolecular aldol reactions with high enantio-selectivities. Moreover, the amino acids can be combined into highly modular natural and unusual small peptides that also catalyze direct asymmetric intermolecular aldol reactions with high stereoselectivities, to furnish the corre sponding aldol products with up to > 99% ee. Simple amino acids and small peptides can thus catalyze asymmetric aldol reactions with stereoselectivities matching those of natural enzymes that have evolved over billions of years. A small amount of water accelerates the asymmetric aldol reactions catalyzed by amino acids and small peptides, and also increases their stereoselectivities. Notably, small peptides and amino acid tetrazoles were able to catalyze direct asymmetric aldol reactions with high enantioselectivities in water, while the parent amino acids, in stark contrast, furnished nearly racemic products. These results suggest that the prebiotic oligomerization of amino acids to peptides may plausibly have been a link in the evolution of the homochirality of sugars. The mechanism and stereochemistry of the reactions are also discussed.
- Cordova, Armando,Zou, Weibiao,Dziedzic, Pawel,Ibrahem, Ismail,Reyes, Efraim,Xu, Yongmei
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p. 5383 - 5397
(2008/02/13)
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- The peptide formation mediated by cyanate revisited. N-carboxyanhydrides as accessible intermediates in the decomposition of N-carbamoylamino acids
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Similar to many ureas, N-carbamoylamino acids were shown to be hydrolyzed in aqueous solution through elimination mechanisms at close to neutral pH, the nucleophilic attack of water being a minor process. Two competing elimination mechanisms can take place involving either cyanate or isocyanate transient intermediates. Peptide formation was observed and attributed to the latter pathway through the intermediacy of amino acid N-carboxyanhydride (NCA). Eventually, cyanate and its precursors (including urea) unexpectedly behave as amino acid activating agents because of their ability in amino acid carbamoylation. Owing to its ability to generate a background prebiotic production of NCAs on the primitive Earth, this reaction is suggested to have contributed to the origin of life process. Copyright
- Danger, Gregoire,Boiteau, Laurent,Cottet, Herve,Pascal, Robert
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p. 7412 - 7413
(2007/10/05)
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- The small peptide-catalyzed direct asymmetric aldol reaction in water
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The asymmetric aldol reaction is a powerful method for forming carbon-carbon bonds. Small peptides with a primary amine as the catalytic residue catalyze asymmetric aqueous aldol reactions between unmodified ketones and aldehydes to furnish the corresponding aldol products with high ees. The high momodularity of the small peptides should enable the construction of several novel catalysts by combinatorial techniques for the aqueous asymmetric aldol reaction. The remarkably high difference in stereoselectivity between the peptide bond-formation was an important step towards the evaluation of asymmetric catalysis and homochilarity.
- Dziedzic, Pawel,Zou, Weibiao,Hafren, Jonas,Cordova, Armando
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- Microorganisms producing dipeptides and process for producing dipeptides using the microorganisms
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The present invention provides microorganisms in which the activities of one or more kinds of peptidases and one or more kinds of proteins having peptide-transporting activity are reduced or lost and which have the ability to produce a dipeptide, microorganisms in which the activities of three or more kinds of peptidases are reduced or lost and which have the ability to produce a dipeptide, and a process for producing dipeptides using the microorganisms.
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- Process for producing dipeptides
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The present invention provides a process for producing a dipeptide which comprises culturing in a medium a microorganism which has the ability to produce a protein having the activity to form the dipeptide from one or more kinds of amino acids and which has the ability to produce at least one of said one or more kinds of amino acids, allowing the dipeptide to form and accumulate in the medium, and recovering the dipeptide from the medium.
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- Process for producing dipeptides or dipeptide derivatives
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The present invention provides a process for producing a dipeptide or a dipeptide derivative using a phosphate donor, a substance selected from the group consisting of adenosine-5′-monophosphate, adenosine-5′-diphosphate and adenosine-5′-triphosphate, one or more kinds of amino acids or amino acid derivatives, and as enzyme sources, a protein having polyphosphate kinase activity, or a culture of cells having the ability to produce the protein or a treated matter of the culture, and a protein having the activity to ATP-dependently form the dipeptide or dipeptide derivative from one or more kinds of amino acids or amino acid derivatives, or a culture of cells having the ability to produce the protein or a treated matter of the culture.
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- Small peptides as modular catalysts for the direct asymmetric aldol reaction: Ancient peptides with aldolase enzyme activity
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Simple peptides and their analogues having a primary amino group as the catalytic residue mediate the direct asymmetric intermolecular aldol reaction with high stereoselectivity and furnish the corresponding aldol products with up to 99% ee; this intrinsic ability of highly modular peptides may explain the initial molecular evolution of aldolase enzymes. The Royal Society of Chemistry 2005.
- Zou, Weibiao,Ibrahem, Ismail,Dziedzic, Pawel,Sunden, Henrik,Cordova, Armando
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p. 4946 - 4948
(2007/10/03)
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- Process for producing dipeptides
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The present invention provides a protein having the activity to synthesize a dipeptide different from L-Ala-L-Ala and a protein for synthesis of the dipeptide, a process for producing the protein having the dipeptide-synthesizing activity, a process for producing the dipeptide using the protein having the dipeptide-synthesizing activity or the protein for the dipeptide synthesis, and a process for producing the dipeptide using a culture of a microorganism producing the protein having the dipeptide-synthesizing activity or the protein for the dipeptide synthesis or the like as an enzyme source.
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- New phototriggers 9: p-Hydroxyphenacyl as a C-terminal photoremovable protecting group for oligopeptides
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In our search for a more versatile protecting group that would exhibit fast release rates for peptides, we have designed and developed the p- hydroxyphenacyl (pHP) group as a new photoremovable protecting group. We report the application of this protecting group for the dipeptide Ala-Ala (1) and for the nonapeptide bradykinin (2), two representative peptides that demonstrate C-terminus 'caging' and photorelease. The synthesis of these p- hydroxyphenacyl esters was accomplished in good yields by DBU-catalyzed displacement of bromide from p-hydroxyphenacyl bromide. As in the case of caged γ-amino acids 11 (pHP glu) and 12 (pHP GABA) and caged nucleotide 17 (pHP ATP) reported earlier, irradiations of the p-hydroxyphenacyl esters of 1 and 2 actuate the release of the peptides with rate constants that are consistently greater than 108 s-1 and appearance efficiencies (Φ(app)) that range from 0.1 to 0.3. Release of the substrate is accompanied by a deep-seated rearrangement of the protecting group into the near-UV silent p- hydroxyphenylacetic acid (6). Quenching studies of pHP Ala-Ala (7) with either sodium 2-naphthalenesulfonate or potassium sorbate gave good Stern- Volmer kinetics yielding a rate constant for release of 1.82 x 108 s-1. Quenching of the phosphorescence emission from pHP Ala-Ala (7, E(T) = 70.1 kcal/mol) and pHP GABA (12, E(T) = 68.9 kcal/mol) were also observed. The biological efficacy of bradykinin released from pHP bradykinin (9) was examined on single rat sensory neurons grown in tissue culture. A single 337 nm flash (1 ns) released sufficient bradykinin from the p-hydroxyphenacyl protected nonapeptide to activate cell-surface bradykinin receptors as indicated by a rapid increase in the intracellular calcium concentration. A selective antagonist of type 2 bradykinin receptors blocked the biological response. From these results, it is apparent that flash photolysis of p- hydroxyphenacyl protected peptides provides a powerful tool for the rapid and localized activation of biological receptors.
- Givens, Richard S.,Weber, Joerg F. W.,Conrad II, Peter G.,Orosz, Gyoergy,Donahue, Sarah L.,Thayer, Stanley A.
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p. 2687 - 2697
(2007/10/03)
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- Rates of reduction of N-chlorinated peptides by sulfite: Relevance to incomplete dechlorination of wastewaters
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Biologically induced fragmentation of proteins during wastewater treatment produces peptides, which form long-lasting organic chloramines when the water is disinfected with Cl2. To protect aquatic wildlife from residual chlorine, including chloramines, wastewaters are often treated with sulfur dioxide or sulfite salts. This strategy incompletely eliminates residual chlorine species. Here we report that dechlorination rate constants of N- chloropeptides are 1-2 orders of magnitude smaller than those for NH2Cl and some aliphatic organic chloramines. Slow rates explain the prevalence of N- chloropeptides in dechlorinated wastewaters after faster reacting chlorine species have been eliminated. Dechlorination is subject to general acid catalysis. For N-chlorinated leucylalanine, the rate law above pH 6 in phosphate buffer at 25 °C and / ? 0.1 M is as follows: rate = (9.92 ± 0.41 x 103[H2PO4-] + 5.70 ± 0.52 x 108[H3O+] + 5.3 ± 0.2)[SO32-][Cl- Leu-Ala] (concentrations in M, time in s). Rate constants for other peptides appear to be of similar magnitude; variations in the acid-catalyzed terms among different hydrophobic peptides correlate with solvation energies of side chains. The kinetic data suggest that reducing N-chloropeptides in wastewaters by 75% or more will require reaction times generally >0.5 h at environmentally acceptable S(IV) doses and pH values. Biologically induced fragmentation of proteins during wastewater treatment produces peptides, which form long-lasting organic chloramines when the water is disinfected with Cl2. To protect aquatic wildlife from residual chlorine, including chloramines, wastewaters are often treated with sulfur dioxide or sulfite salts. This strategy incompletely eliminates residual chlorine species. Here we report that dechlorination rate constants of N-chloropeptides are 1-2 orders of magnitude smaller than those for NH2Cl and some aliphatic organic chloramines. Slow rates explain the prevalence of N-chloropeptides in dechlorinated wastewaters after faster reacting chlorine species have been eliminated. Dechlorination is subject to general acid catalysis. For N-chlorinated leucylalanine, the rate law above pH 6 in phosphate buffer at 25 °C and I≈0.1 M is as follows: rate = (9.92±0.41×103[H2 PO4- ]+5.70±0.52×108[ H3O+]+5.3±0.2) [SO32-][Cl-Leu-Ala] (concentrations in M, time in s). Rate constants for other peptides appear to be of similar magnitude; variations in the acid-catalyzed terms among different hydrophobic peptides correlate with solvation energies of side chains. The kinetic data suggest that reducing N-chloropeptides in wastewaters by 75% or more will require reaction times generally >0.5 h at environmentally acceptable SIV doses and pH values.
- Jensen, James S.,Helz, George R.
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p. 516 - 522
(2007/10/03)
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- Polypeptide, DNA fragment encoding the same, drug composition containing the same and process for producing the same
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This invention particularly provides a novel polypeptide having high protease-inhibiting activity, preferably FXa-inhibiting activity, which comprises, at least as a part of the polypeptide, an amino acid sequence resulting from substitution of an amino acid for at least one amino acid in the following amino acid sequence (1), wherein the amino acid substitution is at least one substitution selected from the following substitution means (i) to (iii). It also provides a process for the production of the polypeptide, a novel DNA fragment encoding the polypeptide and a drug composition containing the same. Amino acid sequence (1) STR1 (i) Substitution of 15 position Gln counting from the N-terminus by an amino acid other than Gln. (ii) Substitution of 42 position Tyr counting from the N-terminus by an amino acid other than Tyr. (iii) Substitution of 7 position Arg counting from the N-terminus by an amino acid other than Arg.
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- Polypeptide, DNA fragment encoding the same, drug composition containing the same and process for producing the same
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This invention particularly provides a novel polypeptide having high protease-inhibiting activity, preferably FXa-inhibiting activity, which comprises, at least as a part of the polypeptide, an amino acid sequence resulting from substitution of an amino acid for at least one amino acid in the following amino acid sequence (1), wherein the amino acid substitution is at least one substitution selected from the following substitution means (i) to (iii). It also provides a process for the production of the polypeptide, a novel DNA fragment encoding the polypeptide and a drug composition containing the same. ______________________________________Amino acid sequence (1)______________________________________Cys Asn Leu Pro Ile Val Arg Gly Pro CysArg Ala Phe Ile Gln Leu Trp Ala Phe AspAla Val Lys Gly Lys Cys Val Leu Phe ProTyr Gly Gly Cys Gln Gly Asn Gly Asn LysPhe Tyr Ser Glu Lys Glu Cys Arg Glu TyrCys______________________________________ (i) Substitution of 15 position Gln counting from the N-terminus by an amino acid other than Gln. (ii) Substitution of 42 position Tyr counting from the N-terminus by an amino acid other than Tyr. (iii) Substitution of 7 position Arg counting from the N-terminus by an amino acid other than Arg.
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- Catalytic properties of X-prolyl dipeptidyl aminopeptidase from Lactococcus lactis subsp. cremoris nTR.
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An X-prolyl dipeptidyl aminopeptidase (X-PDAP; EC 3.4.14.5) was identified to be loosely bound on the inner cell membrane fraction of Lactococcus lactis subsp. cremoris nTR. The biosynthesis of X-PDAP was continuously increased before the late-log growth phase of the bacteria. Both Gly-Pro-pNA and Ala-Ala-pNA were hydrolyzed by X-PDAP; the kcat/Km value of the former was about 10-fold that of the latter. The Ki of X-Pro and Pro-X were more specific to X-PDAP than those of X-Ala. The enzyme splitting a dipeptide sequentially from beta-casomorphin as a model catalytic pattern was identified and some properties of the enzyme were further characterized.
- Yan,Ho,Hou
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p. 704 - 707
(2007/10/02)
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- PEPTIDE ELASTASE INHIBITORS AND METHODS
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Compounds useful as inhibitors of the enzyme elastase are of the following general formula: STR1 wherein Z is selected from the group consisting of R"O--Suc--where R" is lower alkyl of 1 to 3 carbon atoms and CF 3 CO--; X is oxygen or sulfur; R' is selected from the group consisting of straight or secondary branch-chained alkyl of 1 to 4 carbon atoms, alkenyl of 2 to 3 carbon atoms, alkynyl of 2 to 4 carbon atoms, cycloalkyl of 3 to 6 carbon atoms, and benzyl, and R is selected from the group consisting of susbstituted or unsubstituted phenyl wherein the substituents are selected from the group consisting of nitro, and pentafluoro; benzyl, CH 2 CF 2 CF 2 CF 3, 1-lower alkyl tetrazolyl, 1-phenyltetrazolyl, 2-thioxo-3-thiazolidinyl-, pyridyl and benzothiazolyl, provided that when R is paranitrophenyl, R' is other than tertiary-butyl, benzyl or cyclohexyl, and when X is sulfur, R is other than benzyl. "
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- Relative Partial Molar Enthalpies and Apparent Molar Volumes of Dipeptides in Aqueous Solution
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Enthalpies of dilution at 25 deg C of aqueous solutions of the dipeptides glycylglycine, glycylalanine and alanylalanine have been determined and used to calculate the partial molar enthalpies of the solvent water in the solutions.The partial molar volumes of these dipeptides are also reported.The results are discussed in terms of the likely solute-solvent interactions.
- Dyke, Shaun H.,Hedwig, Gavin R.,Watson, Ian D.
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p. 321 - 332
(2007/10/02)
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- The Steric Hindrance of the Stepwise Reaction of N-Carboxy α-Amino Acid Anhydride with the α-Amino Acid Ester
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The mechanisms of the reactions of 4-alkyloxazolidinediones (1) (N-carboxy α-amino acid anhydrides(NCAs)) with α-amino acid benzyl ester p-toluenesulfonates (2) were investigated in acetonitrile containing triethylamine at low and room temperatures.Two types of reactions were observed: (1) the polymerization of NCAs was initiated with a small amount of 2 to produce polypeptides (6), and (2) the dipeptide benzyl esters (4) were produced by the stepwise reaction of NCAs with the esters.Both the polymerization and the dipeptide formation (1+2) seemed to be initiated by the nucleophilic attack of the amino group of the ester on the C-5 carbon of NCAs.The polymerization proceeded when the side chains of the amino acid esters (R2) were more bulky than those of the NCAs (R1).On the contrary, dipeptide esters were produced when the side chains of the NCAs (R1) were more bulky than those of the esters (R2).
- Oya, Masanao,Takahashi, Tomoko
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p. 2705 - 2707
(2007/10/02)
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- PREPARATIVE ISOLATION AND PROPERTIES OF DIASTEREOMERIC COPPER(II) CHELATES OF SCHIFF BASES OF DIPEPTIDES WITH (α-(N,N-DIMETHYLAMINO)ALKYL)FORMYLCYMANTRENES
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The effect of the planar and central chirality of 1,2-(α-(N,N-dimethylamino)alkyl)formylcymantrene on the chromatographic properties of diastereomeric chelates of Cu2+ with Schiff bases from dipeptides and the aminoalkylformylcymantrenes, 1-(N,
- Tsiryapkin, V. A.,Loim, N. M.,Nedospasova, L. V.,Parnes, Z. N.,Belikov, V. M.,Kursanov, D. N.
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- [Asn2 ]-thymosin α1 and analogs thereof
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Thymosin α1, was chemically synthesized by the fragment condensation of the protected amino terminal tetradecapeptide with the protected carboxyl terminal tetradecapeptide. Similarly prepared was the analog [Asn2 ]-thymosin α1 utilizing the appropriately modified protected amino terminal tetradecapeptide. Both products are active as agents which affect regulation, differentiation and function of thymus dependent lymphocytes (T cells).
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