A novel extracellular carbohydrase produced by Lipomyces tetrasporus

Abstract

The ascosporogenous yeast Lipomyces tetrasporus produced an unusual extracellular carbohydrase. It was purified to homogeneity using ammonium sulphate precipitation and DEAE Bio-gel A ion-exchange chromatography. While retaining highest activity on low-molecular:weight saccharides such as maltose and nigerose, it displays considerable activity towards polymeric substrates including soluble starch. It is particularly unusual in that it also hydrolyses dextran and has a very high affinity for this substrate. The enzyme has an exo-lytic mode of action with the only hydrolysis product, glucose, being released in the aanomeric form. Optimum activity occurs at pH 4.5 and at 50 ° C. It is a glycoprotein, and has an Mr value of 150000 (sodium dodecyl sulphate-polyacrylamide gel electrophoresis) -183 000 (fast protein liquid chromatography) and a pI of 6.0.