Large scale purification of myo-inositol monophosphate phosphatase from porcine brains.
myo-Inositol monophosphate phosphatase (IMPase) has been purified 888-fold to apparent homogeneity from procine brains. The purification procedure involves: homogenization, ammonium sulfate fractionation, and a number of ion-exchange and gel-filtration chromatography steps. The purified enzyme exhibited a final specific activity of 932 nmol . min(-1) . mg(-1). The molecular mass of the enzyme was estimated to be 29kDa by SDS poly-acrylamide gel electrophoresis and 58 +/- 5 kDa by HPLC gel filtration in 10mM Tris-HCI, pH 7.4. Kinetic measurements have shown that the apparent K(m) value of the phosphatase for the utilization of inositol-1-phosphate and beta-glycerol phosphate are 3.20 x 10(-4) and 8 x 10(-3) M, respectively. Similar to the same enzyme isolated from bovine brains, the porcine brain enzyme has been shown to be inhibited by lithium. The K(1) was determined to be 6.38 x 10(-4) M and the inhibition is uncompetitive. (c) 1995 John Wiley & Sons, Inc.
Kwok
F
F
Department of Applied Biology and Chemical Technology, Hong Kong Polytechnic University, Hung Hom, Hong Kong.
Wang
X H
XH
Cheng
C H
CH
Lo
S C
SC