title: Protease activities in carp retina.
abstract: Protease of carp retina were examined by electrophoresis and fluorogenic assays. A 70 kD serine protease with an alkaline pH optimum was detected in gelatin-containing polyacrylamide gels. A similar enzyme was found in carp brain and muscle, but not in lens. Using aminomethylcoumarin (MCA) substrates, activities that hydrolysed Z-Phe-Arg-MCA, Boc-Ala-Gly-Pro-Arg-MCA and various aminoacyl-MCAs were detected. The Z-Phe-Arg-MCA hydrolase was an acidic cysteine protease, whereas the Boc-Ala-Gly-Pro-Arg-MCA hydrolase was an alkaline cysteine protease. All aminoacyl hydrolase activities tested were inhibited by bestatin and o-phenanthroline, but not by inhibitors of serine, cysteine and aspartic proteases, suggesting they are metalloaminopeptidases. Of the substrates tested, Tyr-MCA was the most readily hydrolysed aminoacyl substrate. Preliminary evidence was obtained suggesting that levels of these activities do not differ between light- and dark-adapted retinae. The proteases have a potential involvement in retinal functioning and show similarities to other proteases known to act in the central nervous system. In particular, the Tyr-MCA hydrolase may be related to an enzyme known to remove the N-terminal tyrosine residue from enkephalin.
authors.affiliation: Department of Biology, Imperial College of Science, Technology and Medicine, London, U.K.
authors.forename: D N
authors.initials: DN
authors.lastname: Floyd
authors.forename: F
authors.initials: F
authors.lastname: Ashall
authors.forename: M B
authors.initials: MB
authors.lastname: Djamgoz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002347:Carps; D003374:Coumarins; D010450:Endopeptidases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D007976:Leupeptins / Q000494:pharmacology; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism; D010618:Phenanthrolines / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D012160:Retina / Q000201:enzymology*; D012697:Serine Endopeptidases / Q000378:metabolism; D014107:Tosyllysine Chloromethyl Ketone / Q000494:pharmacology
chemical_list: D003374:Coumarins; D007976:Leupeptins; D010455:Peptides; D010618:Phenanthrolines; D011480:Protease Inhibitors; D014107:Tosyllysine Chloromethyl Ketone; D010450:Endopeptidases; D012697:Serine Endopeptidases; D007930:Leucine; C012211:ubenimex; C032854:leupeptin; C025205:1,10-phenanthroline