title: Monte Carlo simulation of multiple attack mechanism of beta-amylase-catalyzed reaction.
abstract: beta-Amylase (EC 3.2.1.2) produces maltose (dimer) from the nonreducing ends of alpha-1,4 glucosidic bonds of substrates like maltooligosaccharides, amylose, and amylopectin. The enzyme releases several maltose molecules from a single enzyme-substrate complex without dissociation by multiple or repetitive attack containing many branching reaction paths. The Monte Carlo method was applied to the simulation of the beta-amylase-catalyzed reaction including the multiple attack mechanism. The simulation starts from a single enzyme molecule and a finite number of substrate molecules. The selection of the substrate by the enzyme and degree of multiple attack proceeds by random numbers produced from a computer. The simulation was carried out until the whole substrate and the intermediate molecules were consumed. The simulated data were compared with experimental data of sweet potato beta-amylase using heptamer, octamer, nanomer, and 11-mer as substrates. The only adjustable parameter for odd-numbered substrates was the probability of multiple attack, while an additional adjustable parameter (a correction factor due to low reactivity of tetramer) was needed for even-numbered substrates.
authors.affiliation: Faculty of Agriculture, Kyoto University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nakatani
mesh_terms: D002384:Catalysis; D020134:Catalytic Domain; D008320:Maltose / Q000378:metabolism; D008954:Models, Biological; D009010:Monte Carlo Method; D013379:Substrate Specificity; D001614:beta-Amylase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D008320:Maltose; D001614:beta-Amylase