Hydrolytic peptides Subject

In Section 7.3, the subject of amino acid analysis is covered including a brief description of hydrolytic techniques, column preparations, and data analysis 7,8 This is followed by a discussion of racemization assays (Section 7.4). These areas of analysis are critically important for researchers in the field of peptide synthesis 9-11 In Section 7.4, a systematic approach is outlined for the study of racemization and mechanisms are discussed for epi-merizations at asymmetric sites. A comparative study is presented for determining the intrinsic rates of racemization, based upon urethane-protected V-carboxy an hydrides (UN-CAs). These approaches are extremely important for understanding the tendencies of novel amino acids and other building blocks to racemize. 

Proteins are subject to a variety of chemical modification/degradation reactions, viz. deamidation, isomerization, hydrolysis, disulfide scrambling, beta-elimination, and oxidation. The principal hydrolytic mechanisms of degradation include peptide bond... 

Stability problems also manifest in vivo. Potential peptide and protein drags are subject to degradation by numerous enzymes or enzyme systems throughout the body. Degradation involves hydrolytic cleavage of peptide bonds by proteases (Figure 1.11) ... 

For the enzymic analysis of polysaccharide structure, the hydrolytic enzymes are the most useful, and little attention will be paid in this article to other types of enzyme. No consideration at all will be accorded enzymes acting on non-carbohydrate moieties. For diis reason, heteropolysaccharide-peptide and lipopolysaccharide complexes (such as those from bacterial cell-walls) are not discussed, as satisfactory treatment of these would also require mention of other types of enzyme, such as amidases for coverage of this subject, an authoritative text and several reviews - may be consulted. Other types of carbohydrate-containing macromolecule, such as glycosaminoglycans ( mucopolysaccharides ) and glycoproteins, for which it is relatively easy to restrict consideration to the polysaccharide portion, are discussed, but only with reference to their carbohydrate moieties. 

We had earlier deduced the total amino acid sequences of some unknown blue-green algal toxic peptides utilizing tandem mass spectrometric techniques in combination with simple chemical modifications and derivatization procedures. The cyclic peptides were hydrolyzed using trifluoroacetic acid. The linear hydrolytic products and their corresponding methyl esters were subjected to FAB ionization and the individual types of ions were analyzed using CID processes. The sequences of the individual peptides were derived from the corresponding recorded MS/MS spectra. Some of the peptides were found to contain Asp and dehydroalanine which had not been observed previously. 

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