Peptide‐Bound Hydroxylysine and Large Polypeptides related to Collagen Synthesis

About 10% of the urinary hydroxylysine is linked to peptides. There is no significant difference between the excretion of peptide-bound hydroxylysine and hydroxylysine measured in the non-dialysable fraction of the urine. Non-dialysable hydroxylysine is highly glycosylated and contains mainly glucosyl-galactosyl-hydroxylysine. It is concluded that the urinary peptide-bound hydroxylysine is present in the non-dialysable collagen polypeptides. Their unusual carbohydrate composition is discussed.