Kinetic studies of alkaline phosphatase extracted from rabbit (Lepus townsendii) liver

  • VO Njoku
  • PC Chikezie
  • AM Kaoje
Keywords: Alkaline phosphatase, Lepus townsendii, 4-nitrophenylphosphate (4-NPP), Arrhenius relationship, Michealis-Menten constant.

Abstract

Studies were carried out to ascertain some kinetic properties of alkaline phosphatase (ALP) extracted from Lepus townsendii liver. Incubation of ALP extract with 4-nitrophenylphosphate (4-NPP) formed the basis for determination of enzyme activity. Spectrophotometric method was used to assay the enzyme activity, and the kinetic constants-maximum enzyme velocity (Vmax) and Michealis-Menten constant (Km) were evaluated. The Km and Vmax values were 0.5 x 10-3 M and 20 x 10-6 M/min, respectively. Inhibition studies showed that ALP activity was competitively inhibited by 0.67 mM sodium hydrogen orthophosphate (NaH2PO4) and the inhibition constant (Ki) was 0.9 x 10-3 M. The optimum pH value for ALP activity was about 9.2, and optimum temperature registered was 45°C. ALP activity exhibited linear Arrhenius relationship at temperature greater than 44.95°C with corresponding catalytic energy of activation (Ea) = 15.23 KJ mole-1. The present study gave insights into characteristic catalytic properties of ALP extracted from L. townsendii liver.

Key words: Alkaline phosphatase, Lepus townsendii,  4-nitrophenylphosphate (4-NPP), Arrhenius relationship, Michealis-Menten constant.

Published
2013-08-29
Section
Articles

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eISSN: 1684-5315