The high maltose-producing α-amylase of the thermophilic actinomycete, Thermomonospora curvata
The high maltose-producing α-amylase of the thermophilic actinomycete, Thermomonospora curvata
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DOI：
10.1007/bf00166844
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发表时间：
1993-04
影响因子：
5
通讯作者：
B. S. Collins;C. Kelly;W. M. Fogarty;E. Doyle
中科院分区：
文献类型：
--
作者：
B. S. Collins;C. Kelly;W. M. Fogarty;E. Doyle
The α-amylase ofThermomonospora curvatacatalyses the formation of very high levels of maltose from starch (73%, w/w) without the attendant production of glucose. The enzyme was produced extracellularly in high yield during batch fermentation in a 5-1 fermentor. Purification was achieved by ammonium sulphate fractionation, Superose-12 gel filtration and DEAE-Sephacel ionexchange chromatography. The enzyme exhibited maxima for activity at pH 6.0 and 65°C, had a relative molecular mass of 60900–62000 and an isoelecric point at 6.2. The exceptionally high levels of maltose produced and the unique action pattern exhibited on starch and related substrates indicate a very unusual maltogenic system. The predominance of maltose as the final end-product may be explained by the participation of reactions other than simple hydrolysis and the preferential cleavage of maltotriose from higher maltooligosaccharides. The enzyme exhibits very low affinity for maltotriose (Km=7.7 × 10−3m) and its conversion to maltose is achieved by synthetic followed by hydrolytic events, which result in the very high levels of maltose observed and preclude glucose formation. This system is distinguished from other very high maltose-producing amylases by virtue of its high temperature maximum, very low affinity for maltotriose and the absence of glucose in the final saccharide mixture.
