Porcine pancreatic alpha-amylase hydrolysis of native starch granules as a function of granule surface area.
Porcine pancreatic alpha-amylase activity on native starch granules is more accurately described as a function of surface area of the granules rather than of substrate concentration. The apparent K(m) of alpha-amylolysis of native starch from potato, maize, and rice expressed as a function of substrate concentration was largest for potato with a single value of V(max). However, the ratio of the slope of a Lineweaver-Burk plot to that of rice for enzymatic hydrolysis of native potato and maize starch were 7.78 and 2.58, respectively, which were very close to the ratio of surface area per mass of the two starch granules to that of rice. Therefore, the reciprocal of initial velocity was a linear function of the reciprocal of surface area for each starch granule. Surface area was calculated assuming the starch granules were spherical. The values obtained by this calculation were in good agreement with the value obtained by the photomicrographic method. By comparing enzymatic digestion of native maize granules to that of rice granules, it was concluded that the presence of pores in maize granules appeared to significantly affect overall rate of digestion after sufficient reaction time, but not at the very initial stage of hydrolysis.
Kong
Byoung-Wook
BW
Food Research Institute and School of Food and Life Science, Institute of Basic Sciences, and Biohealth Products Research Center, Inje University, Gimhae 621-749, Republic of Korea.
Kim
Jung-In
JI
Kim
Myo-Jeong
MJ
Kim
Jae Cherl
JC
D000818:Animals; D004789:Enzyme Activation; D006868:Hydrolysis; D007700:Kinetics; D008863:Microspheres; D008956:Models, Chemical; D012275:Oryza / Q000737:chemistry*; D010179:Pancreas / Q000737:chemistry / Q000201:enzymology; D010316:Particle Size; D011198:Solanum tuberosum / Q000737:chemistry*; D013213:Starch / Q000737:chemistry* / Q000648:ultrastructure*; D013379:Substrate Specificity; D013499:Surface Properties; D013552:Swine; D003313:Zea mays / Q000737:chemistry*; D000516:alpha-Amylases / Q000737:chemistry* / Q000378:metabolism
D013213:Starch; D000516:alpha-Amylases