Differenzierung aliphatischer Dipeptidasen aus Dorschmuskel

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Abstract
The hydrolysis of a large number of dipeptides was studied with the aid of a continuous spectrophotometric assay (225 to 230 [mu]m, depending on the substrate). Using glycyl-L-leucine as substrate, 1 enzymic activity was purified about 250-fold. The various dipeptidases may be differentiated by preparative steps in the enzyme purification, like pH-controlled heat denaturation and DEAE-cellulose chromatography, with or without the presence of Zn2 ; the effects of chelation by EDTA and of subsequent reactivation by Zn or Ma ions; formation of mercaptides of sulfydryl groups with p-chloromercuribenzoate; kinetic data like product inhibition and pH-activity curves. On the basis of these criteria, 5 distinct enzymes are present in cod muscle, with specificity for: L-leucyl-glycine, L-valyl-glycine and L-phenylalanyl-glycine; glycyl-L-threonme, glycyl-L-serine and glycyl-L-alanine; L-alanyl-glycine and L-seryl-glycine; glycyl-L-leucine, glycyl-L-isoleucine, glycyl-L-valine and glycyl-L-phenylalanine and glycyl-L-methionine. There is probably a large number of other distinct dipeptidases.