INHIBITION OF REDUCED DP18-MALTODEXTRIN AND AMYLOSE HYDROLYSIS BY ACARBOSE - KINETIC-STUDIES

Kinetics of inhibition of porcine pancreatic a-amylase by acarbose wer e performed using maltodextrin and amylose as substrates. Similar Line weaver-Burk primary plots were obtained. Two mixed non-competitive mod els are proposed. X-ray crystallographic data (Qian, M., Buisson, G., Duee, E., Haser, R. and Payan, F. Biochemistry, 1994; 33: 6284-6294) a re in support of the mixed non-competitive inhibition model which invo lves abortive complexes. Secondary plots are different indicating that in the maltodextrin hydrolysis, one molecule of acarbose is bound per amylase molecule, while using amylose as substrate two molecules of a carbose are bound. These two kinetically determined binding sites migh t correspond to the two surface sites shown by X-ray crystallography ( Qian, M., Haser, R. and Payan, F. Protein Science 1995; 4: 747-755). ( C) 1997 Elsevier Science B.V.