Glycopeptides peptide chain

Glycopeptides containing a 2-acetamido-N-(L-aspart-4-oyl)-2-deoxy-/ -D-glucopyranosylamine residue (11) may be synthesized either by direct addition of the carbohydrate residue to the peptide chain, or by elongation of the peptide chain from 11 in the direction of the carboxylic, or the amino, terminal. 

Elongation of the peptide chain in the direction of the N-terminal by a solid-phase procedure was introduced by Lavielle and coworkers,132 who prepared the glycopeptide [3-0-(2-acetamido-2-deoxy-/ -D-gluco-pyranosyl)-L-serine]-L-glycyl-L-alanine (189) by first coupling 168, de-protected by hydrogenolysis, to an L-alanyl resin (188), and, after re-... 

One of the most characteristic differences between papain and the other sulfhydryl proteases, ficin and bromelain, is the absence of carbohydrate in papain. Glycopeptides have been isolated from ficin (48) and bromelain (49, 50, 51, 52). In the case of bromelain the carbohydrate moiety composed of mannose, xylose, fucose, and N-acetylglucosamine is covalently linked to an asparagine residue of the peptide chain through a glucosamine component of the sugar moiety (51,52). 

Unlike mammalian cells, bacterial cells are surrounded by a fairly rigid cell wall, which allows the bacterium to live in many different environments. This protective cell wall is composed of carbohydrates linked together by peptide chains containing amide linkages, formed using the enzyme glycopeptide transpeptidase. 

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