Comparative characterization of raw starch hydrolyzing α-amylases from various Bacillus strains

Two saccharifying alpha-amylases with. different molecular masses were purified from Bacillus subtilis IFO 3108. The higher molecular mass alpha-amylase I (RBSA-1, MM 67 kDa) was able to adsorb to alpha-cyclodextrin (a-Cl)) sepharose CL-6B and hydrolyze raw starch. RBSA-1 showed weak adsorption to raw corn starch over the wide pH range of 5.0-9.0. At low pH (5.0-6.0), RBSA-1 exhibited high adsorption to raw potato starch. The lower molecular mass (x-amylase 2 (BSA-2, MM 45 kDa) exhibited enzymatic properties similar to RBSA-1, however, was unable to adsorb to alpha-Cl) sepharose CL-6B and failed to hydrolyze raw starch. On the other hand, a liquefying type alpha-amylase (RBLA), purified from Bacillus sp., exhibited remarkable adsorption to raw starches tested over a wide pH range (5.0-9.0). This pH range corresponded to that suitable for the digestion of raw starches. The adsorption of RBSA-1 and RBLA to alpha-CD sepharose CL-6B was pH-independent, however, the extent of adsorption of RBSA-1 (70-85%) was, much greater than that of RBLA (30-45%). The hydrolysis of raw corn starch was specifically inhibited by (alpha-CD for both enzymes. The K-i value (0.44 m-M) for RBSA-1 was much lower than that for RBLA (3.44 mM). (c) 2005 Elsevier Inc. All rights reserved.