The effect of granule surface area on hydrolysis of native starches by pullulanase

Abstract

AbstractVarious native starch granules were reacted as substrates for a debranching enzyme, pullulanase, from Bacillus acidopullulyticus, and the kinetic mechanism was investigated in initial rate studies. The apparent Km values of the native starch hydrolysis reactions decreased in the order of rice, corn, and potato, whereas Vmax remained constant for all starches. Assuming that starch granules were spherical, the double reciprocal of the initial rates of the hydrolysis reactions along with the surface area of the three native starch granules could be described in a linear function. Therefore, enzymatic hydrolysis of native starches during the initial stage is mainly affected by particle size of starch granules. Further, the surface area as well as particle size of granules have important effects on the initial rate at which native starch is digested by debranching enzyme. We believe that this is the first systematic study reporting kinetic data on the effect of granule surface area on hydrolysis of native starches by α‐1,6‐glucan hydrolase.