HYDROXYLATION OF COLLAGEN TYPE-I - EVIDENCE THAT BOTH LYSYL AND PROLYL RESIDUES ARE OVERHYDROXYLATED IN OSTEOGENESIS IMPERFECTA

The composition of the collagens secreted into the media of fibroblast cultures of 39 patients with osteogenesis imperfecta (OI) was the sam e in controls and OI cultures. An abnormal migration pattern of collag ens upon SDS-PAGE was evident in one third of the cultures investigate d. Lysyl and prolyl hydroxylation of HPLC-purified alpha 1(I) chains w as elevated in about 60% of cultures. The degree of hydroxylation was highest in the lethal forms. The extent of lysyl and prolyl hydroxylat ion showed a strong correlation (r = 0.74, P < 0.001). While high leve ls of hydroxylation are frequently observed in OI patients, a direct c orrelation between lysyl of prolyl hydroxylation and fracture rate or growth retardation could not be established.