Diphenolases from Anoxybacillus kestanbolensis strains K1 and K4 T

Diphenolases from Anoxybacillus kestanbolensis strains K1 and K4^sup T^, highly active against 4-methylcatechol were characterized in terms of pH- and temperature-optima, pH- and temperature-stability, kinetic parameters, and inhibition/activation behaviour towards some general polyphenol oxidase (PPO) inhibitors and metal ions. The temperature-activity optima, for Anoxybacillus kestanbolensis K1 and K4^sup T^ catecholases in the presence of 4-methylcatechol, were 80 and 70 °C, respectively. Although catecholase from A. kestanbolensis K4^sup T^ lost no activity after a period of 1 h incubation at its optimum temperature, the enzyme pH from K1 was stimulated by keeping at 80 °C. Both of the enzymes possessed pH optima at 9.5, and the pH-stability profiles showed that cathecholases from both preparations retained their activities at alkaline pH values. Both A. kestanbolensis K1 and K4^sup T^ catecholase activities were totally inhibited by addition of 0.01 mM sodium metabisulphite, ascorbic acid and l-cysteine. 1 mM Mn^sup 2+^ increased the activities of A. kestanbolensis K1 and K4^sup T^ catecholases by 6.4- and 5.3-fold, respectively. These results indicate that both A. kestanbolensis K1 and K4^sup T^ strains possess thermo- and alkalostable catecholases.[PUBLICATION ABSTRACT]