The enzymic deacylation of esterified mono- and di-saccharides. I. The isolation and purification of an esterase from wheat germ lipase

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Abstract
Whereas wheat germ lipase was known to contain acid phosphatase (EC 3.1.3.2), esterase (EC 3.1.1.1), and lipase (EC 3.1.1.3) activity, a cursory examination of some commercial enzymes has demonstrated also the presence of phosphodiesterase (EC 3.1.4.1), α- and β-glucosidase (EC 3.2.1.20 and EC 3.2.1.21), α- and β-galactosidase (EC 3.2.1.22 and EC 3.2.1.23), α-mannosidase (EC 3.2.1.24), and β-xylosidase (EC 3.2.1.37) activities. Disc electrophoresis revealed a minimum of 12 electrophoretically distinct protein fractions. Different sources and different batches of enzyme had similar disc electrophoretic behavior and activities. Fractionation of the crude preparation on carboxymethylcellulose or Sephadex, and electrophoresis on Sephadex, failed to separate α-glucosidase and esterase activities. The inhibition of α- and β-glucosidase could be effected by D-glucono-1,5-lactone, but not by metal salts or Tris.Preparative polyacrylamide-gel electrophoresis of wheat germ lipase gave a large number of active zones including several esterases, acid phosphatase, and α- and β-glucosidase fractions. Evidence was established for the nonidentity of two neighboring esterase zones. One was found to be free of α- and β-glucosidase activity. Sulfhydryl reagents inhibited the esterases, whereas acetone activated some and inactivated others. The esterases were most stable at neutral pH and were extensively inactivated on lyophilization, dialysis, and desalting with molecular-sieving reagents. Some properties of the purified esterase were examined.
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