Bound hydroxyproline excretion following gelatin loading in prolidase deficiency.
The excretion of peptide-bound hydroxyproline before and after gelatin loading was evaluated in two children with prolidase deficiency, two adult heterozygotes, and normal controls. On a low hydroxyproline diet, the patients with prolidase deficiency excreted 6.9 and 2.4 times more bound hydroxyproline than normal children. The bound hydroxyproline excretion for the heterozygotes was comparable to the adult controls. Children ingested 20 g of gelatin and adults 29 g. In the 24 hr following gelatin loading, the homozygotes excreted 14.4 and 17.3 times more of the ingested load of hydroxyproline than did normal children. This constituted 39% and 47% of the hydroxyproline ingested. Of the hydroxyproline excreted in 24 hr, 58%, and 61.4% was excreted in the first 6 hr. Over the 24 hr period, the normal children excreted 2.7% of the hydroxyproline ingested (97.8% in the first 6 hr). The heterozygotes excreted only slightly more than the adult controls. The normal adults excreted 6.0% of the ingested hydroxyproline (82.8% in the first 6 hr). In prolidase deficiency, large amounts of peptide-bound hydroxyproline can cross the intestinal wall unhydrolyzed. Prolidase appears to have an important role in normal hydrolysis of peptide-bound hydroxyproline.
D000328:Adult; D000592:Amino Acid Metabolism, Inborn Errors / Q000235:genetics; D002648:Child; D002986:Clinical Trials as Topic; D004150:Dipeptidases / Q000172:deficiency*; D005260:Female; D005780:Gelatin / Q000378:metabolism*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D006868:Hydrolysis; D006909:Hydroxyproline / Q000378:metabolism / Q000652:urine*; D007408:Intestinal Absorption; D008297:Male
D005780:Gelatin; D004150:Dipeptidases; D006909:Hydroxyproline