Hydroxyproline Peptides of Urine in Arthritic Patients and Controls on a Collagen-Free Diet.

Abstract

The amino acid composition of 5 hydroxyproline peptides isolated from urine of control subjects on a collagen-free diet is reported. There is no evidence of the 2 peptides previously isolated from a patient with rheumatoid arthritis. Hydroxyproline peptides separated by 2-dimensional paper chromatography following Dowex 50 chromatography from 3 arthritic urines and 2 controls on a collagen-free diet have been analyzed for amino acid composition. One peptide did not stain with either ninydrin or with chlorine gas-starch iodide, and was assumed to be either the diketopiperazine of proline and hydroxyproline or a conjugated peptide of these amino acids with acetyl or other sub-stituent. It was present in all of the patients, was not detected in 1 of the control subjects, and was found in smaller amount in the other control. A procedure is described by which this peptide can be separated essentially free of other hydroxyproline contaminants.