Dipeptidyl-aminopeptidases and aminopeptidases in Dictyostelium discoideum.

S A Chan, K Toursarkissian, J P Sweeney, T H Jones

Index: Biochem. Biophys. Res. Commun. 127 , 962, (1985)

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Abstract

Extracts prepared from culminating cells of Dictyostelium discoideum have been found to contain dipeptidyl-aminopeptidases I (EC 3.4.14.1), II (EC 3.4.14.2), III (EC 3.4.14.4), arginine aminopeptidase (EC 3.4.11.6) and valine aminopeptidase. Dipeptidyl-aminopeptidase III was the most active of the dipeptidyl-aminopeptidases; its molecular weight was 158,000, with a pH optimum of 10.2 and gave a single peak of activity on gel-filtration or when fractionated by chromatofocusing. The specific activities of dipeptidyl-aminopeptidases I and III increased during development being highest during the culmination stage before decreasing during sorocarp formation; dipeptidyl-aminopeptidase II and arginine aminopeptidase decreased progressively throughout development. The presence of these dipeptidyl-aminopeptidases suggests the possibility that processing of peptides may be necessary during the development of Dictyostelium.