Evidence on the presence of two distinct alkaline phosphatases in Serratiamarcescens

Certain strains of Serratia marcescens synthesized two different types of a lkaline phosphatase (APase), constitutive (CAPase) and inducible (IAPase) A Pases, in low phosphate medium. Synthesis of the IAPase was repressed in th e presence of high phosphate. Purification and separation of these electrop horetically distinct APases was achieved by using fractional (NH4)(2)SO4 pr ecipitation, adsorption on a DEAE-cellulose column and elution of enzymes b y a linear sodium chloride gradient. Starch gel electrophoresis of certain fractions revealed the separation of not only IAPase from CAPase but its se paration into four distinct isozymes. CAPase gave maximum enzyme activity a round pH 9.5, whereas for IAPase a broad range of enzyme activity was found between pH 8.5 and 10.5. Reversible inactivation at low pH occurred for IA Pase but very little with CAPase. CAPase was more thermolabile than IAPase at 95 degrees C. The two APases were found to be distinct in their kinetic as well as immunological properties, suggesting two distinct enzyme species . Crown copyright (C) 2000 Published by Elsevier Science B.V. All rights re served.