Peptides and Amides

Solid state 2H NMR has been used to obtain detailed structural information for the amide and carboxylic acid hydrogen sites in a single crystal of the model peptide N-acetyl-D,L-valine [134]. Both the amide and carboxylic acid hydrogens are involved in intermolecular hydrogen bonds. The results were compared with experimental data obtained for acetylanilide [135] and ab initio calculations for glycylglycine [136]. 

2H EFG and chemical shift tensors for all the exchangeable deuteron sites in the model dipeptide glycylglycine monohydrochloride have been determined [71]. 

For all three sites at room temperature, the principal axis corresponding to the largest component of each EFG tensor lies nearly along the appropriate bond. Specifically, the carboxylic acid deuteron tensor deviates by only ca. 3° from the 

The nature of the hydrogen bonding in polymorphs of AT-benzoyl-D,L-phen-ylalanine and N-benzoyl-L-phenylalanine has been investigated by solid state 13C NMR [137]. 

The multiple resonances observed for the carbon of the carboxylic acid group in N-benzoyl-L-phenylalanine were shown to be related to different types of hydrogen bonding. These results are in good agreement with earlier studies using 

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L. Crespo, G. Sanclimens, M. Pons, E. Giralt, M. Royo, and F. Albericio, Peptide and amide bond-containing dendrimers, Chem. Rev., 105 (2005) 1663-1681. 

Solvolysis Amino acid esters, peptides, and amides Cu- Co2+. Mn t... 

Steps in the hydrolysis of p-nitrophenyl acetate by chymotrypsin. In the hydrolysis of this and most other esters, the breakdown of the acyl-enzyme intermediate is the rate-determining step. In the hydrolysis of peptides and amides, the rate-determining step usually is the formation of the acyl-enzyme intermediate. This makes the transient formation of the intermediate more difficult to study because the intermediate breaks down as rapidly as it forms. 

Arid Hydrolysis. Boiling a protein with 10% HC1 for several hours hydrolyzed all of its peptide and amide bonds. Short treatments produced short polypeptides the longer the treatment, the more complete the breakdown of the protein into its amino acids. 

Hydrolysis. Two types of hydrolytic reactions occur in proteins at alkaline pH. These are the hydrolysis of peptide and amide bonds and the hydrolysis of arginine to ornithine. Amide bonds are hydrolyzed rapidly in alkaline solution probably as shown in Equation 4 (21). 

Kern et. aL employed poly(styrenesulfonic add) 2 and poly(ethylenesulfonic add) 3 for the hydrolysis of some peptides and amides. The catalytic activity of these water-soluble polymers were three to five times greater than the same concentrations of HQ and H2SO4 (12,13). The molecular weight of the polymer did not influence the catalytic efficiency. 

Phenylalanylglycine amide was found to undergo ring closure to form 3-benzyl-2,5-diketopiperazine in the absence of metal ions (reaction XLI). In the presence of copper(II) at pH 5, the protonated form of the amide underwent hydrolysis reactions at both the peptide and amide bonds. 

AlbericioF (2004). Developments in peptides and amide synthesis. Curr. Opin. Chem. Biol. 8 211-221. 

The final chapter, by Itokawa, Takeya, Hitotsuyanagi, and Morita, reviews the various macrocyclic peptide alkaloids isolated from plants. In addition to a general overview of the many new peptide and amide alkaloids that have been isolated recently from a diverse range of plant families, this review places particular emphasis on the structure-activity relationships, the conformational analysis, and the antitumor activity of the RA series of cyclic oligopeptides from Rubia spp. 

Hydrolysis of peptide and amide linkages is also a possible complication in an alkaline medium. Hydrolysis of the amide groups of the residues of aspartic and glutamic acids will increase the ratio of acidic to basic groups in the fibers, conceivably altering the isoelectric and/or isoionic points of the hair. 

In another paper Faerman and Price [90] present a very detailed set of DMA results (especially in the supplementary material) concerning peptides and amides (from 3-21G wavefunctions). The main interest of this contribution is the attention paid by the authors to the transferability of the multipole descriptions. Both papers demonstrate the inadequacy of Mulliken charges for the description of the MEP as well as in representing the transferability properties of the groups. 

BIOSYNTHESIS OF NON-CYCLOL d-LYSERGIC ACID PEPTIDES AND AMIDES... 

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