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Studies with proline-3,4-H3 on the hydroxylation of proline during collagen synthesis in chick embryos

1964; Elsevier BV; Volume: 106; Linguagem: Inglês

10.1016/0003-9861(64)90163-8

1096-0384

Darwin J. Prockop, Paul S. Ebert, Bennett M. Shapiro,

TGF-β signaling in diseases

The recent availability of proline-3,4-H3 has appeared to make it possible to define the mechanism involved in the hydroxylation of proline during collagen synthesis in some detail, but conflicting results with this compound have been reported. Further studies with a mixture of proline-3,4-H3 and uniformly labeled proline-C14 indicated that about 73% of the tritium is retained during the hydroxylation reaction. Enzymatic and chemical degradation of the proline-3,4-H3 employed in the experiments indicated that essentially all of the tritium label was in the 3- and 4-carbon positions. Evidence about the relative distribution of tritium among the four hydrogen positions on the 3- and 4-carbon atoms was not obtained, but a detailed examination of the possible distributions of label and of the possible intermediates in the hydroxylation indicated that 4-ketoproline or 3,4-dehydroproline could not have occurred as intermediates during the hydroxylation unless several improbable assumptions were made. The results, therefore, were interpreted as indicating that tritium from a single hydrogen position was lost in the conversion of proline-3,4-H3 to collagen hydroxyproline.