PROPERTIES AND SIGNIFICANCE OF AN ALPHA-AMYLASE PRODUCED BY MYXOCOCCUS-CORALLOIDES-D

The extracellular amylase activity from Myxococcus coralloides D was p urified by Sephacryl S-200 gel filtration and by ion-exchange chromato graphy on DEAE-Sephadex A-25. The molecular weight was estimated by SD S-PAGE and by gel filtration as 22.5 kDa. The optimum temperature was 45 degrees C. The pH range of high activity was between 6.5 and 8.5, w ith an optimum at pH 8.0. Activity was strongly inhibited by Hg2+, Zn2 +, CU2+, Ag+, Pb2+, Fe2+ and Fe3+, EDTA and glutardialdehyde, but was less affected by Ni2+ and Cd2+.Li+, Mg2+, Ba2+, Ca2+, N-ethylmaleimide , carbodiimide and phenyl methyl sulphonyl fluoride had almost no affe ct. The K-m (45 degrees C, pH 8) for starch hydrolysis was 2.0 x 10(-3 ) g l(-1). Comparison of the blue value-reducing curves with the time of appearance of maltose identified the enzyme produced by M. coralloi des D as an alpha-amylase.