18875-39-3Relevant academic research and scientific papers
Influence of the amino acid side chain on peptide bond hydrolysis catalyzed by a dimeric Zr(iv)-substituted Keggin type polyoxometalate
Ly, Hong Giang T.,Absillis, Gregory,Parac-Vogt, Tatjana N.
, p. 976 - 984 (2016)
Peptide bond hydrolysis of 18 different dipeptides, divided into four groups depending on the nature of the amino acid side chain, by the dimeric Zr(iv)-substituted Keggin type polyoxometalate (POM) (Et2NH2)8[{α-PW11O39Zr-(μ-OH)(H2O)}2]·7H2O (1) was studied by means of kinetic experiments and 1H/13C NMR spectroscopy. The observed rate constants highly depend on the bulkiness and chemical nature of the X amino acid side chain. X-Ser and X-Thr dipeptides showed increased reactivity due to intramolecular nucleophilic attack of the hydroxyl group in the side chain on the amide carbon, resulting in a reactive ester intermediate. A similar effect in which the amino acid side chain acted as an internal nucleophile was observed for the hydrolysis of Gly-Asp. Interestingly, in the presence of 1 deamidation of Gly-Asn and Gly-Gln into Gly-Asp and Gly-Glu was observed. Dipeptides containing positively charged amino acid side chains were hydrolyzed at higher rates due to electrostatic interactions between the negatively charged POM surface and positive amino acid side chains.
New insights into the palladium-mediated selective hydrolysis of the His18-Thr19 peptide bond in cytochrome c: 1H NMR and density functional theory investigation for model compounds
Sun, Xiao-Juan,Zhang, Lin,Zhang, Yu,Yang, Gao-Sheng,Guo, Zi-Jian,Zhu, Long-Gen
, p. 818 - 822 (2003)
The peptides, CH3CO-Met-His-GlyH, CH3CO-CysMe-His-GlyH, CH3CO-CysMe-His-Gly-OEt and its imidazole derivatives, Nτ-benzyl, Nτ-tosyl, N-benzyl-Nπ-phenacyl, have been synthesized and used as model compounds for the mechanistic study of the selective cleavage of cytochrome c promoted by Pd(II) complexes. The peptide bond cleavage of these substrates by cis-[Pd(en)(solvent)2]2+ (solvent: D2O or CD3OD) was monitored by 1H NMR spectroscopy. The results showed that the methionine-containing tripeptide differs from the S-methylcysteine-containing tripeptides in the mode of coordination to Pd(II). The former coordinates to Pd(II) through a sulfur atom, an amide nitrogen of methionine and an Nπ atom of imidazole, forming a polycyclic chelate, and is resistant to hydrolysis. The latter, as a model compound for cleavage of the His18-Thr19 bond in cytochrome c with Pd(II) complexes, coordinates to Pd(II) via a sulfur atom, an amide nitrogen and a carbonyl oxygen of histidine to form a polycyclic chelate in which the His-Gly peptide bond is cleaved. Kinetic studies showed that protonation of the Nπ atom of imidazole in the S-methylcysteine-containing tripeptides is one of the key factors in controlling the cleavage of the His-Gly bond. In order to obtain theoretical guidance on the cleavage reaction, the geometries of a representative Nπ protonated tripeptide cation of CH3CO-CysMe-His-GlyNMe and its Pd(II) complex with and without ancillary water molecules are optimized at the B3LYP density functional theory level using 3-21G, 6-31G(d) and LanL2DZ basis sets. Based on the experimental and theoretical results obtained from the model compounds, a mechanism is proposed for the first time to explain the nature of selective cleavage of the His18-Thr19 bond in cytochrome c promoted by Pd(II) complexes. Coordination of Pd(II) to the carbonyl oxygen of histidine and hydrogen bond formed between the C=O and ancillary dimer water weaken and polarize the C=O double bond of histidine, giving rise to cleavage of the peptide bond.
Some properties of glycine aminotransferase purified from Rhodopseudomonas palustris No. 7 concerning extracellular porphyrin production.
Yamaguchi, Hidetoshi,Ohtani, Masahiro,Amachi, Seigo,Shinoyama, Hirofumi,Fujii, Takaaki
, p. 783 - 789 (2003)
Glycine aminotransferase (EC 2.6.1.4; GlyAT) was presumed to be an enzyme concerning the supply of glycine for the extracellular porphyrin production by Rhodopseudomonas palustris No. 7. GlyAT was purified from strain No. 7 as an electrophoretically homogenous protein. The enzyme was a monomer protein with the molecular weight of about 42,000. From the absorption spectrum of the enzyme (350 nm, 410 nm), it was indicated that the enzyme had pyridoxal phosphate as a prosthetic group. The enzyme showed high substrate specificity for glutamate as an amino group donor. Apparent Kms for glutamate and glyoxylate were 6.20 mM and 3.75 mM, respectively. The Vmax and Kcat for glutamate were 66.8 mumol/min/mg protein and 46.8 s-1, respectively. The Vmax and Kcat for glyoxylate were 68.8 mumol/min/mg protein and 48.2 s-1. The optimum temperature and pH were 40-45 degrees C and 7.0-7.5, respectively. The enzyme activity lowered to about 50% in the presence of 15 mM ammonium chloride.
Kinetics and mechanism of base hydrolysis of a-aminoacid esters catalysed by [pd(1,3-diamino-2-hydroxypropane)(H2O)2]2+ complex
Al-Qalaf,Al Bassam,Shoukry
, p. 1706 - 1708 (2013)
Amino acid esters (L) react with [Pd(DHP(H2O)2] 2+ , (DHP = 1,3-diamino-2-hydroxopropane) giving mixed ligand [Pd(DHP)L]2+ The kinetics of hydrolysis of [Pd(DHP)L]2+ have been studied by pH-stat technique and rate constants were obtained. Rate acceleration observed for glycine methyl ester is high. The effect with methionine methyl ester and histidine methyl ester are much less marked, as the mixed-ligand complexes with these ligands do not involve alkoxycarbonyl donors. Possible mechanisms for these reactions are considered. Activation parameters have been determined for glycine methyl ester.
Abiotic asparagine formation from simple amino acids by contact glow discharge electrolysis
Munegumi, Toratane,Shimoyama, Akira,Harada, Kaoru
, p. 393 - 394 (1997)
Asparagine, one of the most important amino acids for prebiotic peptide formation in aqueous media, was formed using Contact Glow Discharge Electrolysis (CGDE) against aqueous solutions containing simple amino acids and carboxylic acid amides.
Glycine enolates: The effect of formation of iminium ions to simple ketones on α-amino carbon acidity and a comparison with pyridoxal iminium ions
Crugeiras, Juan,Rios, Ana,Riveiros, Enrique,Amyes, Tina L.,Richard, John P.
, p. 2041 - 2050 (2008)
Equilibrium constants in D2O were determined by 1H NMR analyses for formation of imines/iminium ions from addition of glycine methyl ester to acetone and from addition of glycine to phenylglyoxylate. First-order rate constants, also determined by 1H NMR, are reported for deuterium exchange between solvent D2O and the α-amino carbon of glycine methyl ester and glycine in the presence of increasing concentrations of ketone and Bronsted bases. These rate and equilibrium data were used to calculate second-order rate constants for deprotonation by DO- and by Bronsted bases of the α-imino carbon of the ketone adducts. Formation of the iminium ion between acetone and glycine methyl ester and between phenylglyoxylate and glycine is estimated to cause 7 unit and 15 unit decreases, respectively, in the pKa's of 21 and 29 for deprotonation of the parent carbon acids. The effect of formation of iminium ions to phenylglyoxylate and to 5′-deoxypyridoxal (DPL) [Toth, K.; Richard, J. P. J. Am. Chem. Soc. 2007, 129, 3013-3021] on the carbon acidity of glycine is similar. However, DPL is a much better catalyst than phenylglyoxylate of deprotonation of glycine, because of the exceptionally large thermodynamic driving force for conversion of the amino acid and DPL to the reactive iminium ion.
Suggested improvement in the ing-manske procedure and Gabriel synthesis of primary amines: Kinetic study on alkaline hydrolysis of N-phthaloylglycine and acid hydrolysis of N-(o-carboxybenzoyl)glycine in aqueous organic solvents
Khan, M. Niyaz
, p. 8063 - 8068 (1996)
A slight modification of the Gabriel synthesis of primary amines is suggested on the basis of the observed and reported values of rate constants for the alkaline and acid hydrolyses of phthalimide, phthalamic acid, benzamide, and their N-substituted derivatives. The suggested procedure requires shorter reactions time and milder acid-base reaction conditions compared with the conventional acid-base hydrolysis in the Gabriel synthesis. A slight modification in the Ing-Manske procedure is also suggested. Pseudo-first-order rate constants, kobs, for hydrolysis of N-phthaloylglycine, NPG, decrease from 24.1 × 10-3 to 7.72 × 10-3 and 6.12 × 10-3 s-1 with increasing acetonitrile and 1,4-dioxan contents, respectively, from 2 to 50% v/v (all the percentages given in the paper are vol %), while increasing the organic cosolvents content from 50 to 80% increases kobs from 7.72 × 10-3 to 19.7 × 10-3 s-1 for acetonitrile and from 6.12 × 10-3 to 52.8 × 10-3 s-1 for 1,4-dioxan, in aqueous organic solvents containing 0.004 M NaOH at 35 °C. The rate constants for NPG hydrolysis decrease from 2.11 × 10-2 to 1.19 × 10-4 s-1 with increasing MeOH content from 2 to 84%, in aqueous organic solvents containing 2% MeCN and 0.004 M NaOH at 35 °C.
The crystal structures of glycylglycine and glycine complexes of cis,cis-1,3,5-triaminocyclohexane-copper(II) as reaction intermediates of metal-promoted peptide hydrolysis
Tan, Xiang Shi,Fujii, Yuki,Sato, Tsuyoshi,Nakano, Yoshiharu,Yashiro, Morio
, p. 881 - 882 (1999)
The glycylglycine and glycine complexes of cis,cis-1,3,5-triaminocyclohexane-copper(II), model reaction intermediates of peptide hydrolysis by Cu(II)-triamine complexes, have been synthesized and characterized by X-ray crystallography.
Mechanism of pH-dependent photolysis of aliphatic amino acids and enantiomeric enrichment of racemic leucine by circularly polarized light.
Nishino,Kosaka,Hembury,Shitomi,Onuki,Inoue
, p. 921 - 924 (2001)
It has been proposed that the origin of biological homochirality may be the result of irradiation of a racemic sample of amino acids by circularly polarized light (CPL). To determine the mechanism of enantiomeric enrichment, the irradiation of aliphatic amino acids by CPL was undertaken. An enantiomerically enriched sample (e.g., L isomer enrichment from r-CPL) was found to result from the preferential excitation/decomposition of one enantiomer over another via a Norrish Type II mechanism (leucine, valine, and isoleucine), with the enantiomeric excess dependent on the degree of protonation of the amino/carboxylic acid moiety.
Effects of linkage isomerism and of acid-base equilibria on reactivity and catalytic turnover in hydrolytic cleavage of histidyl peptides coordinated to palladium(II). Identification of the active complex between palladium(II) and the histidyl residue
Parac, Tatjana N.,Kostié, Nenad M.
, p. 5946 - 5951 (1996)
This is a quantitative study of hydrolysis of the His-Gly bond in the peptide AcHis-Gly catalyzed by cis-[Pd(en)(H2O)2]2+. We exploit the diverse coordinating abilities and acid-base properties of histidyl residue to interpret the kinetics and explain the mechanism of this new reaction. We compare peptides selectively methylated at the N-1 or N-3 atom of imidazole and study effects of solution acidity on the abundance of different peptide-catalyst complexes and on the rate constant for hydrolysis. Only the catalyst bound to the N-3 atom of imidazole can effect this reaction; none of the four other modes of coordination is effective. The necessary approach of the palladium(II) aqua complex to the scissile peptide bond and the rate constant of hydrolysis are unaffected by the remote methyl group that merely controls the mode of peptide coordination to the catalyst. Acid in solution affects hydrolysis only by controlling the concentration of the reactive complex, not by catalyzing the reaction itself. Weakly acidic solution is required to suppress oligomerization of the catalyst. Hydrolytic cleavage occurs with a turnover greater than 4. With the half-life of 5.1 h at pH 5.0, the cleavage is fast enough at relatively mild conditions to be practical for various applications in biochemistry and structural biology. This study is an important step in our development of palladium(II) complexes as artificial metallopeptidases.
