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

Summary 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. The chromatographic pattern of hydroxyproline from Dowex 50 ion exchange columns is shown to be quite similar for the 3 arthritic urines and 2 controls on the collagen-free diet. Hydroxyproline peptides separated by 2-dimensional chromatography on paper from such columns have been analyzed for amino acid composition. One peptide containing only proline and hydroxyproline, present in all of the patients, was not detected in one of the 2 control urines. The significance of this finding is discussed, and a procedure is described by which this peptide can be separated essentially free of other hydroxyproline contaminants.