Determination of hydroxyproline polypeptides in urine and blood serum by gel filtration.

Hydroxyproline-containing polypeptides were isolated from urine by filtration on polyacrylamide gel Bio-Gel P-2. This fraction was quantitatively and qualitatively similar to the nondialysable hydroxyproline in urines of normal adult subjects, patients with chronic uremia, and with primary or secondary hyperparathyroidism. Hydroxyproline polypeptides isolated from urines of patients with extensive Paget's disease or from normal growing subjects contained a group of smaller polypeptides slightly retarded on Bio-Gel P-2 which were not retained by the dialysis membrane Spectrapor-TM. In these two groups of subjects the values of hydroxyproline polypeptides were 35-45 percent higher than those of dialysable hydroxyproline. Increased excretion of hydroxyproline polypeptides was found in chronic uremia, primary and secondary hyperparathyroidism, Paget's bone disease and in normal growing subjects. With the notable exception of chronic uremia the excretion of hydroxyproline polypeptides paralleled that of total and oligopeptidic hydroxyproline. In some cases of chronic uremia the polypeptidic hydroxyproline represented the predominant fraction. On long columns of Bio-Gel P-6 hydroxyproline polypeptides separated into several peaks. The chromatographic pattern was rather characteristic for chronic uremia, secondary hyperparathyroidism, Paget's bone disease and physiological growth. Ahydroxyproline fraction of similar chromatographic properties was isolated from blood serum after deproteinisation with heat or ethanol at pH 4.8. High serum levels of this hydroxyproline fraction were observed in pathological conditions with increased urinary excretion of polypeptidic and nondialysable hydroxyproline.