title: Cysteine and serine protease-mediated proteolysis in body homogenate of a zooplankter, Moina macrocopa, is inhibited by the toxic cyanobacterium, Microcystis aeruginosa PCC7806.
abstract: The paper describes the characterization of proteases in the whole body homogenate of Moina macrocopa, which can possibly be inhibited by the extracts of Microcystis aeruginosa PCC7806. With the use of oligopeptide substrates and specific inhibitors, we detected the activities of trypsin, chymotrypsin, elastase and cysteine protease. Cysteine protease, the predominant enzyme behind proteolysis of a natural substrate, casein, was partially purified by gel filtration. The substrate SDS-polyacrylamide gel electrophoresis of body homogenate revealed the presence of nine bands of proteases (17-72 kDa). The apparent molecular mass of an exclusive cysteine protease was 60 kDa, whereas of trypsin, it was 17-24 kDa. An extract of M. aeruginosa PCC7806 significantly inhibited the activities of trypsin, chymotrypsin and cysteine protease in M. macrocopa body homogenate at estimated IC(50) of 6- to 79-microg dry mass mL(-1). Upon fractionation by C-18 solid-phase extraction, 60% methanolic elute contained all the protease inhibitors, and these metabolites could be further separated by reverse-phase liquid chromatography. The metabolites inhibitory to M. macrocopa proteases also inhibited the corresponding class of proteases of mammalian/plant origin. The study suggests that protease inhibition may contribute to chemical interaction of cyanobacteria and crustacean zooplankton.
authors.affiliation: Department of Biological Sciences, Rani Durgavati University, Jabalpur 482001, India.
authors.forename: Manish Kumar
authors.initials: MK
authors.lastname: Agrawal
authors.forename: Divya
authors.initials: D
authors.lastname: Bagchi
authors.forename: Suvendra Nath
authors.initials: SN
authors.lastname: Bagchi
mesh_terms: D000818:Animals; D001586:Benzoylarginine Nitroanilide / Q000378:metabolism; D002364:Caseins / Q000378:metabolism; D002918:Chymotrypsin / Q000378:metabolism; D033361:Cladocera / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D046931:Microcystis / Q000502:physiology*; D008970:Molecular Weight; D010196:Pancreatic Elastase / Q000378:metabolism; D011506:Proteins / Q000187:drug effects / Q000378:metabolism; D012697:Serine Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D014357:Trypsin / Q000378:metabolism; D015048:Zooplankton
chemical_list: D002364:Caseins; D015853:Cysteine Proteinase Inhibitors; D011506:Proteins; D001586:Benzoylarginine Nitroanilide; D012697:Serine Endopeptidases; D002918:Chymotrypsin; D010196:Pancreatic Elastase; D014357:Trypsin; D003546:Cysteine Endopeptidases