Purification and partial characterisation of a bovine kidney aminotripeptidase (capable of cleaving prolyl-glycylglycine).

An enzyme was purified 163-fold in an 8.2% yield from bovine kidney. The specific activities of the pure preparation against L-prolyl glycylglycine and L-alanyl glycylglycine were found to be 244.5 and 578 micron Moles substrate hydrolyzed per min per mg protein respectively. The molecular weight of the enzyme was estimated on gel filtration to be 55,000. The isoelectric point was recorded to be pH 5.2. A preliminary study of substrate specificity showed that the enzyme preferentially hydrolyzed tripeptides of the type X-glycylglycine. The enzyme was tentatively identified as a tripeptide aminopeptidase (alpha aminoacyldipeptide hydrolase, EC 3.4.11.4).