Hydroxylysyl residues

Hydroxylation of prolyl residues and some lysyl residues glycosylation of some hydroxylysyl residues... 

Oxidative deamination ofe-amino groups of lysyl and hydroxylysyl residues to aldehydes... 

This enzyme [EC 1.4.3.13], also referred to as protein-lysine 6-oxidase, catalyzes the reaction of a peptidyl-L-lysyl-peptide with dioxygen and water to produce a peptidyl-allysyl-peptide, ammonia, and hydrogen peroxide. The enzyme will also act on 5-hydroxylysyl residues in proteins. 

Collagens are extracellular proteins of connective tissue and they make up about one third of all body protein. They are a family of related glycoproteins in which hydroxylysyl residues provide the sites for attachment... 

Oxidative deamination of e-amino groups of strategically located lysyl and hydroxylysyl residues to provide reactive aldehydes. These form cross-linkages between polypeptide chains of the same molecule as well as between the adjacent molecules that give strength and stability to the fibrils. 

The intracellular protein-making machinery first of all produces polypeptide a-chains (approximately 1000 amino acids). Some of the prolyl and lysyl residues are hydroxylated by reactions that need vitamin C (Chapter 56). Some of the hydroxylysyl residues are glycosylated. The units then associate to form the triple helix (rope-like) procollagen, which is soluble. 

This allows the condensation of the aldehyde group with amino hydroxylysyl residue in the other chain to produce the corresponding imine. Amadori rearrangement of the imine produces a stable inter-chain bridge. This process leads to cross-linking of tropoe-lastin and continues to form desmosine and isodesmosine units (2-98) containing a pyridine nucleus and connecting the individual chains to form extremely resistant protein elastin. 

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