title: Extracellular transglucosylase and alpha-amylase of Streptococcus equinus.
abstract: Culture filtrates of Streptococcus equinus 1091 contained alpha-amylase and transglucosylase. The effects of calcium carbonate, age of inoculum, concentration of maltose, and duration of the fermentation on alpha-amylase and transglucosylase production were determined. The extracellular alpha-amylase was purified 48-fold and was free of transglucosylase activity. The alpha-amylase (amylose substrate) required Cl(-) for maximum activity; ethylenediaminetetraacetic acid (EDTA) partially inhibited activity, but CaCl(2) prevented EDTA inhibition. The temperature optimum was 38 C at pH 7.0, and the pH optimum was 7.0 at 37 C in the presence of CaCl(2). Predominant final products of amylose hydrolysis, in order of decreasing prevalence, were maltose, maltotriose, maltotetraose, and glucose. The alpha-amylase showed no evidence of multiple attack. The extracellular transglucosylase was purified 27-fold, but a small amount of alpha-amylase remained. Transglucosylase activity (amylose substrate) was not increased in the presence of CaCl(2). The temperature optimum was 37 C at pH 6.5, and the pH optimum was 6.0 at 37 C. Carbohydrates that served as acceptors for the transglucosylase to degrade amylose were, in order of decreasing acceptor efficiency: d-glucose, d-mannose, l-sorbose, maltose, sucrose, and trehalose. The extracellular transglucosylase of S. equinus 1091 synthesized higher maltodextrins in the medium when the cells were grown in the presence of maltose.
mesh_terms: D000096:Acetone; D000681:Amylases / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D002122:Calcium Chloride; D050260:Carbohydrate Metabolism; D002474:Cell-Free System; D011232:Chemical Precipitation; D002712:Chlorides / Q000494:pharmacology; D002848:Chromatography, DEAE-Cellulose; D002854:Chromatography, Paper; D003470:Culture Media; D003956:Dialysis; D004492:Edetic Acid / Q000494:pharmacology; D004579:Electron Transport; D005285:Fermentation; D005374:Filtration; D005964:Glucosyltransferases / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008970:Molecular Weight; D013045:Species Specificity; D013213:Starch / Q000378:metabolism; D013291:Streptococcus / Q000145:classification / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D013696:Temperature
chemical_list: D002712:Chlorides; D003470:Culture Media; D000096:Acetone; D013213:Starch; D004492:Edetic Acid; D005964:Glucosyltransferases; D000681:Amylases; D002122:Calcium Chloride; D002118:Calcium