Purification of two exoglucanases secreted by Saccharomyces cerevisiae and partial characterization of their protein moieties.
Growth of Saccharomyces cerevisiae cells in a synthetic buffered culture medium resulted in the secretion of high levels of two soluble exoglucanases which were purified by a procedure involving one (exglucanase II) and two (exoglucanase I) steps, respectively. Once treated with endoglucosaminidase H (Endo H) both enzymes behaved indistinguishably when analyzed by SDS-PAGE, high pressure liquid chromatography (HPLC) and ionic exchange chromatography. Exoglucanase I, the isoenzyme with higher carbohydrate content, exhibited a higher Km against laminarin and a higher thermal stability than exoglucanase II. However, once the enzymes were deglycosylated in vitro these parameters turned out to be identical. These results suggest that both exoglucanases share a very similar, if not identical protein portion and accordingly may be product of either the same gene or a family of related genes.
Ramírez
M
M
Departamento de Microbiología, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain.
Andaluz
E
E
Larriba
G
G
D043326:Glucan 1,3-beta-Glucosidase; D005959:Glucosidases / Q000302:isolation & purification*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D001617:beta-Glucosidase / Q000096:biosynthesis / Q000145:classification / Q000302:isolation & purification*
D005959:Glucosidases; D001617:beta-Glucosidase; D043326:Glucan 1,3-beta-Glucosidase