PURIFICATION AND PROPERTIES OF AN EXTRACELLULAR ALPHA-AMYLASE FROM THERMUS SP

An extracellular alpha-amylase from an extreme thermophile, Thermus sp ., was highly purified by affinity absorption on starch granules. SDS PAGE showed a single band for the purified enzyme, with an apparent mo lecular weight of 59000. The optimum pH and temperature for the enzyme action on starch was 5.5-6.5 and 70 degrees C, respectively. The enzy me randomly attacked the bonds in the inner region of the starch and p roduced various maltooligosaccharides. The minimum length of maltoolig osaccharide cleaved by this enzyme was maltohexaose. The enzyme activi ty was strongly inhibited by the addition of Cu2+ and Fe2+ ions. The e nzyme belonged to the EDTA-sensitive alpha-amylase group, but its acti vity was not stimulated by the presence of Ca2+ ions.