Glucosyl modification

Further enzymatic modifications allowed the isolation of the glucosylated derivatives 12a (60 times more soluble than 12) and of the acid derivative 12b, which was three orders of magnitude more soluble [35]. 

A quite different situation holds for collagen in which P-galactosyl units and glucosyl-P-galactosyl disaccharide units are attached to side chains of hydroxy-lysine formed by postsynthetic modification of the original procollagen chain. 

Figure 3 Posttranslational modifications in collagen, (a) 3(S)-hydroxyproline. (b) 4(R)-hydroxyproline. (c) 5-hydroxylysine. (d) O-p-galactosyl-5-hydroxylysine. (e) 2-0-a-D-glucosyl-0-p-D-galactosyl-5-hydroxylysine.

Proteins undergo several other modifications in addition to phosphorylation, glucosylation, and ubiquitination discussed above. Some of these include proteolysis, acetylation, methylation, sulfonation, frensylation, and sumoy-lation. 

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