Protease activity in gut of Daphnia magna: evidence for trypsin and chymotrypsin enzymes.
Comp Biochem Physiol B Biochem Mol Biol
; 137(3): 287-96, 2004 Mar.
Article
in En
| MEDLINE
| ID: mdl-15050516
ABSTRACT
Two major protease activities were present in gut homogenates of the cladoceran crustacean Daphnia magna (i) a trypsin activity that hydrolysed the synthetic substrate N-benzoyl-dl-arginine p-nitroanilide and was strongly inhibited by N-p-tosyl-lysine chloroketone (TLCK) and 4-(amidinophenyl)methanesulfonyl fluoride (APMSF) and not inhibited by chymostatin; and (ii) a chymotrypsin activity that hydrolysed synthetic chymotrypsin substrates containing more than one amino acid, did not hydrolyse N-benzoyl-l-tyrosine p-nitroanilide, and was strongly inhibited by chymostatin and not by TLCK and APMSF. Both activities had alkaline pH optima (pH 7-10), but were shown to be due to distinct types of proteases. These two enzyme activities accounted for 75-83% of the proteolytic activity of gut contents. Substrate SDS-polyacrylamide gel electrophoresis revealed nine different proteases ranging from 15 to 73 kDa.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Serine Endopeptidases
/
Daphnia
/
Intestines
Limits:
Animals
Language:
En
Journal:
Comp Biochem Physiol B Biochem Mol Biol
Journal subject:
BIOLOGIA MOLECULAR
/
BIOQUIMICA
Year:
2004
Document type:
Article
Affiliation country:
Germany