PROLYL HYDROXYLASE-ACTIVITY IN TISSUE-HOMOGENATES OF ANNELIDS FROM DEEP-SEA HYDROTHERMAL VENTS

Tissue homogenates of the deep sea annelids Alvinella caudata and Alvi nella pompejana were found to contain enzyme activity resembling verte brate prolyl 4-hydroxylase. The release of (H2O)-H-3 from [3,4-H-3]pro line labeled, under-hydroxylated chicken protocollagen type I depended on the presence of the cofactors 2-oxoglutarate, ascorbate, Fe2+ and O-2. The release of (H2O)-H-3 could be inhibited by the prolyl 4-hydro xylase inhibitors zinc, 2,2'-dipyridyl, 3,4-dihydroxybenzoic acid and pyridine-2,4-dicarboxylate, as well as by the synthetic pep tide (Pro- Pro-Gly)(10). This synthetic peptide could also serve as substrate, be cause it enhanced the decarboxylation of 2-oxo[5-C-14]glutarate. Alvin ella prolyl hydroxylase appeared to be related to type II vertebrate e nzyme because of its lack of affinity for poly (L-proline) and resista nce to inactivation by an irreversible peptide inhibitor of chicken pr olyl 4-hydroxylase. Maximal enzyme activity was observed in solutions with less than 10% oxygen saturation. By contrast, chicken enzyme was most active at saturating oxygen concentrations. Further data suggest that the Alvinella enzymes are able to accept the 2-oxo acids pyruvate , oxaloacetate and 2-oxoadipinate as substitutes of the cosubstarate 2 -oxoglutarate. The data explain the high hydroxylation of Alvinella co llagens despite the low oxygen concentrations around hydrothermal vent s.