Enzymatic Cleavage of Peptides

Substitution of the l-amino acids with their D-amino acid configurational analogue, will enhance resistance to enzymatic cleavage of peptide bonds. The ll isomer of cyclo(Leu-Leu) hydrolyzes 3.5 times faster than the DL isomer in the presence of 0.5 moll HCl. This difference was explained by both steric shielding ui-trans isomer) and steric strain (ll- j isomer). ... 

The bond cleavage detection was validated using the enzymatic cleavage of peptides by a-chymotrypsin, and the important features for the success of the... 

This setup of pEMR and MMC is particularly well suited to link enzymatic cleavage of peptides, for instance, cytochrome c digested with trypsin, with a chromatographic separation of the peptide fragments that are analyzed by MALDI-TOF coupled to the pEMR/MMC device. 

Non-Enzymatic Cleavage of Peptide Chains at the Cysteine and Serine Residues. 

Morishita, M., and F. Sakiyama The non-enzymatic Cleavage of Peptide Bonds. II. The Chemical Cleavage of the Tryptophyl Bond in Several Synthetic Peptides. Bull. Chem. Soc. Japan 43, 524-530 (1970). 

The enzymatic cleavage of esters is a vast and extensively reviewed area of chemistry. Recently, several new esters have been examined primarily for the preparation of peptides and glycopeptides. 

Larsen et al. reported the enzymatic cleavage of a desB30 insuhn B-chain from a presequence (Lys(Boc))6. This spacer shifts the conformation of the growing peptide chain from a y9-structure to a random coil conformation and reduces pep-tide-chain aggregation, which otherwise causes serious synthetic problems. Nova-syn KA [18] was employed as a solid support, but unfortunately, no information about the enzyme used was reported [19]. 

Lowe et al. investigated the substrate selectivity of the proteases papain and chy-motrypsin using PEGA-bound combinatorial peptide hbraries (32) (Fig. 10.3) [24]. The quahtative extent of enzymatic cleavage of the resin-bound peptide in case of an accepted substrate strand was rapidly visualized by a significant reduction in the fluorescence of the beads visuahzed with a fluorescence microscope. Furthermore it was proven that substrate selectivity of the enzyme remain the same on the solid phase and in solution. 

Enzymatic cleavage of the thioester bond (located either in the middle or at the C-terminus of the peptide) produces a free thiol compound that can be easily monitored by very sensitive assays (e.g., Ellman s reagent). 64 ... 

Heizmann, J., et al. 1996. Enzymatic cleavage of thymopoietin oligopeptides by pancreatic and intestinal brush-border enzymes. Peptides 17 1083. 

Fig. 12. Stepwise enzymatic cleavage of human angiotensinogen X = peptide fragment of angiotensinogen...

Enzymatic cleavage of hydrophilic peptides from casein. 

Chemical and enzymatic methods for the selective cleavage of peptide bonds are not completely separate either-or propositions. In addition chemical modification may well be combined with enzymatic degradation in a manner which promises new usages and more selectivity for proteinases and peptidases in sequence studies. 

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