Prolylhydroxyproline in urine: Its determination and observations in muscular dystrophy

A method is described for the quantitative determination of prolylhydroxyproline in urine by isotope dilution after addition of synthetic [ 14C]dipeptide. The method consists of (1) high voltage paper electrophoresis at pH 2, (2) chromatography in the system butanol-acetic acid-water, (3) conversion of dipeptide to diketopiperazine, (4) a second chromatography in the same system, (5) determination of hydroxyproline and radioactivity. Values of prolylhydroxyproline are reported in eight patients with pseudohypertrophic muscular dystrophy and four normal controls on a collagen-free diet. Two of the patients had higher values of dipeptide in percentage of total hydroxyproline than any of the controls. The significance of the results is discussed.