Partial purification and characterization of midgut leucyl aminopeptidase of Morimus funereus (Coleoptera: Cerambycidae) larvae.
Exopeptidases of Morimus funereus larvae were partially purified and characterized. Specific leucyl aminopeptidase (LAP) activity was increased eight-fold by gel filtration of the crude midgut extract. The partially purified LAP had a molecular mass greater than 100 kDa with pH optima from 7.0-9.0 and no strict substrate specificity. M. funereus LAP preferentially hydrolyzed p-nitroanilides with hydrophobic amino acids in the active site, with a K(m) for leucine-p-nitroanilide of 0.21 mM. Zymogram analysis of an electropherogram obtained by native polyacrylamide gel electrophoresis revealed four enzymatically active proteinases using leucine-p-nitroanilide and methionine-p-nitroanilide as substrates and two enzymatically active proteinases using lysine-p-nitroanilide as a substrate. Although the optimal temperature of LAP activity was 40 degrees C, the enzyme was active over a broad temperature range from 2 to 60 degrees C. Among a number of inhibitors tested, heavy metals and 1,10-phenanthroline completely inhibited the enzyme, while methanol, ethanol and EGTA stimulated somewhat LAP activity.
Bozić
Natasa
N
Department of Biochemistry, Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade, Yugoslavia. n.bozic@eunet.yu
Vujcić
Zoran
Z
Nenadović
Vera
V
Ivanović
Jelisaveta
J
D000818:Animals; D001517:Coleoptera / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007814:Larva / Q000201:enzymology*; D007931:Leucyl Aminopeptidase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D013270:Stomach / Q000201:enzymology; D013379:Substrate Specificity; D013696:Temperature
D007931:Leucyl Aminopeptidase