14464-29-0Relevant articles and documents
The role of methionine-192 of the chymotrypsin active site in the binding and catalysis of mono(amino acid) and peptide substrates.
Greadway Jr.,Schultz
, p. 4171,4172 (1976)
We find that specific oxidation for the Met-192 residue in delta-chymotrypsin to methionine sulfoxide results in a twofold increase in Km(app) and unchanged kcat in the hydrolysis of N-acetyl mono(amino acid) amide substrates. However, the catalyzed hydrolyses of N-acetyl dipeptide amide substrates by (methionine sulfoxide)-192-delta-chymotrypsin (MS-delta-Cht) shows a four- to fivefold decrease in kcat and unchanged Km(app) with respect to delta-chymotrypsin. Hydrolysis of alpha-casein by MS-delta-Cht shows a similar 4.2-fold decrease in kcat. These results imply that the Met-192 acts differently with substrates that bind only in the primary, S1, binding site (i.e., AcPheNH2) from those that bind to more extended regions of the enzyme active site. In the binding of c+AcPheNH2 and AcTrpNH2, the results support a mechanism in which the Met-192 acts to slow the rate of sustrate dissociation from the Michaelis complex to free substrate and enzyme. This is in agreement with the x-ray crystallographic structure of dioxane inhibited alpha-chymotrypsin (Steitz, T., et al. (1969), J. Mol. Biol. 46, 337). However, this mechanism is not apparent when peptide and protein substrates bind. The decrease in kcat on Met-192 modification of approximately fivefold in the hydrolysis of polypeptide substrates show a small, but significant, catalytic contribution of the Met-192 toward the lowering of the energy of activation polypeptide substrate hydrolysis by chymotrypsin. This may support the crystallographic model of Fersht et al. (Fersht, A., et al. (1973), Biochemistry 12, 2035) in which it is proposed that the Met-192 participates in the distortion of bound polypeptide substrates toward the reaction transition-state configuration and, thus, plays a role in catalysis. However, if this mechanism occurs, the effect is small, only contributing about 1 kcal/mol to the lowering of the reaction activation energy.
Noncanonical amino acids to improve the pH response of pHLIP insertion at tumor acidity
Onyango, Joab O.,Chung, Michael S.,Eng, Chee-Huat,Klees, Lukas M.,Langenbacher, Rachel,Yao, Lan,An, Ming
, p. 3658 - 3663 (2015)
The pH low insertion peptide (pHLIP) offers the potential to deliver drugs selectively to the cytoplasm of cancer cells based on tumor acidosis. The WT pHLIP inserts into membranes with a pH50 of 6.1, while most solid tumors have extracellular pH (pHe) of 6.5-7.0. To close this gap, a SAR study was carried out to search for pHLIP variants with improved pH response. Replacing Asp25 with α-aminoadipic acid (Aad) adjusts the pH50 to 6.74, matching average tumor acidity, and replacing Asp14 with γ-carboxyglutamic acid (Gla) increases the sharpness of pH response (transition over 0.5 instead of 1 pH unit). These effects are additive: the Asp14Gla/Asp25Aad double variant shows a pH50 of 6.79, with sharper transition than Asp25Aad. Furthermore, the advantage of the double variant over WT pHLIP in terms of cargo delivery was demonstrated in turn-on fluorescence assays and anti-proliferation studies (using paclitaxel as cargo) in A549 lung cancer cells at pH 6.6.
Development of n new class of rate-accelerating additives for nitroxide- mediated 'living' free radical polymerization
Malmstroem, Eva,Miller, Robert D.,Hawker, Craig J.
, p. 15225 - 15236 (1997)
Acylating agents have been identified as a new class of rate accelerating additives for nitroxide-mediated 'living' free radical polymerization. It is found that addition of 1 weight percent of acetic anhydride results in a significant decrease in the reaction time, 48 to 4 hours. This decrease in reaction time leads to greater control over the polymerization process with low polydispersity materials being obtained up to 150 000 a.m.u. A possible explanation for this effect is acylation of the alkoxyamine nitrogen leading to an increase in the lability of the C-ON bond.
Synthesis of N-hydroxysuccinimide esters using polymer bound HOBT
Dendrinos, Kleanthis G.,Kalivretenos, Aristotle G.
, p. 1321 - 1324 (1998)
The preparation of the N-hydroxysuccinimide esters via reactions mediated by polymer bound 1-hydrozybenzotriazole (HOBT) is reported.
A New Method for the Preparation of Active Esters Using Di-2-pyridyl Carbonate
Kim, Sunggak,Ko, Young Kwan
, p. 473 (1985)
The use of di-2-pyridyl carbonate in the presence of a catalytic amount of 4-dimethylaminopyridine is found to be very effective in the preparation of various active esters.
Enhanced sample multiplexing for nitrotyrosine-modified proteins using combined precursor isotopic labeling and isobaric tagging
Robinson, Ren? A. S.,Evans, Adam R.
, p. 4677 - 4686 (2012)
Current strategies for identification and quantification of 3-nitrotyrosine (3NT) post-translationally modified proteins (PTM) generally rely on biotin/avidin enrichment. Quantitative approaches have been demonstrated which employ isotopic labeling or isobaric tagging in order to quantify differences in the relative abundances of 3NT-modified proteins in two or potentially eight samples, respectively. Here, we present a novel strategy which uses combined precursor isotopic labeling and isobaric tagging (cPILOT) to increase the multiplexing capability of quantifying 3NT-modified proteins to 12 or 16 samples using commercially available tandem mass tags (TMT) or isobaric tags for relative and absolute quantification (iTRAQ), respectively. This strategy employs "light" and "heavy" labeled acetyl groups to block both N-termini and lysine residues of tryptic peptides. Next, 3NT is reduced to 3-aminotyrosine (3AT) using sodium dithionite followed by derivatization of light and heavy labeled 3AT-peptides with either TMT or iTRAQ multiplex reagents. We demonstrate the proof-of-principle utility of cPILOT with in vitro nitrated bovine serum albumin (BSA) and mouse splenic proteins using TMT 0, TMT6, and iTRAQ8 reagents and discuss limitations of the strategy.
NMR investigations of the conformation of new cyclodextrin-based amphiphilic transporters for hydrophobic drugs: molecular lollipops
Bellanger, Nathalie,Perly, Bruno
, p. 215 - 226 (1992)
Amphiphilic compounds, obtained by grafting aliphatic acids onto a modified cyclodextrin, have been synthesized and studied by solution NMR.The large chain-length dependence of the NMR spectra in aqueous media is explained by the possible formation of auto-inclusion complexes.This process has been evidenced by extensive NMR experiments and by competition with potential guests.This new class of molecules ("lollipops") provides important information for the optimization of a design for amphiphilic transporters to be included in organized phases such as micelles or liposomes.
Formation of 1-hydroxymethylene-1,1-bisphosphinates through the addition of a silylated phosphonite on various trivalent derivatives
Dussart-Gautheret, Jade,Deschamp, Julia,Monteil, Maelle,Gager, Olivier,Legigan, Thibaut,Migianu-Griffoni, Evelyne,Lecouvey, Marc
, p. 14559 - 14569 (2020/12/29)
An easily handled one-pot synthetic procedure was previously developed for the synthesis of bisphosphinates starting from acyl chlorides. Herein, other trivalent derivatives as acid anhydrides and activated esters were tested to form various bisphosphinates. This modulation of the reactivity can be controlled according to the nature of the acid derivative for the use of sensitive and functionalized substrates.
Synthesis and In Vitro Neuroprotective Activity of Glycine Analogs of Gk-2 Dimeric Dipeptide Mimetic of Nerve Growth Factor 4th Loop
Antipov, P. I.,Antipova, T. A.,Firsova, Yu. N.,Gudasheva, T. A.,Nikolaev, S. V.,Rebeko, A. G.,Sazonova, N. M.,Tarasyuk, A. V.,Zvyagintsev, A. A.
, (2020/05/28)
A dimeric dipeptide mimetic of nerve growth factor (NGF), bis-(N-monosuccinyl-L-glutamyl-L-lysine) hexamethylenediamide (GK-2), was previously developed at V. V. Zakusov State Institute of Pharmacology, activated specific TrkA receptors, and exhibited neuroprotective activity in vitro (10–5 – 10–9 M) and in vivo (0.1 – 10 mg/kg i.p. and p.o.). GK-2 was designed based on the beta-turn (-Asp94-Glu95-Lys96-Gln97-) of the NGF 4th loop and preserved the central dipeptide fragment (-Glu95-Lys96-). The Asp94 residue was replaced by its monosuccinyl bioisostere. The dimeric structure of NGF was reproduced using a bivalent hexamethylenediamine spacer. The structure—activity (neuroprotective) relationship for GK-2 was studied in the present work using a glycine scan, i.e., successive replacement of the peptide side groups by H. The bis-(N-acetyl-L-glutamyl-L-lysine) (GK-2Ac), bis-(N-monosuccinylglycyl-L-lysine) (GK-2-Gly1), and bis-(N-monosuccinyl-L-glutamylglycine) hexamethylenediamides (GK-2-Gly2) were less active with neuroprotective activity in vitro under oxidative stress for HT22 cells at concentrations 10 – 100 times greater than GK-2. The conclusion was drawn that each side radical of GK-2 was important for manifestation of the full neuroprotective activity of dimeric dipeptide GK-2, a mimetic of the NGF 4th loop. However, removal of any of the side radicals would probably not change the active structure of the beta-turn so that the two remaining side radicals should retain the ability to bind to their TrkA subsites. This could explain the retention of neuroprotective activity in the GK-2 glycine analogs.
DIPEPTIDE MIMETICS OF NGF AND BDNF NEUROTROPHINS
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Paragraph 0181; 0182, (2019/04/16)
The invention relates to compounds having either agonist or antagonist activities for the neurotrophins NGF and BDNF and represented by monomeric or dimeric substituted dipeptides that are analogs of the exposed portions of loop 1 or loop 4 regions of these neurotrophins near or at a beta-turn of the respective loop. N-acylated substituents of these dipeptides are biostereoisomers of the amino acid residues preceding these dipeptide sequences in the neurotrophin primary structure. The dimeric structure is produced advantageously by using hexatnethylenediaanine to which dipeptides are attached via their carboxyl groups. The claimed compounds displayed neuroprotective and differentiation-inducing activities in cellular models and enhanced the amount of phosphorylated tyrosine kinase A and the heat shock proteins Hsp32 and Hsp70 in the concentration range of 10 -9 to 10 -5 M. They also displayed neuroprotective, anti-parkinsonian, anti-stroke, anti-ischemic, anti-depressant and anti-amnestic activities in animal models and were active in experimental models of Alzheimer's disease. These in vivo effects of the claimed compounds are displayed in the dose range of 0.01 to 10 mg/kg when administered intraperitoneally.
