Exo-glucosidase activity and substrate specificity of the beta-glycosidase isolated from the extreme thermophile Sulfolobus solfataricus.
The enzyme with beta-galactosidase activity from Sulfolobus solfataricus strain MT-4, like other enzymes of this type isolated from thermophilic sources, has broad specificity for beta-D-gluco-, fuco- and galacto-sides. The beta-galactosidase activity was purified by a new procedure that improved yields (44%) and final specific activity (182 units mg-1 at 75 degrees C using chromogenic beta-D-galactoside as substrate). The enzyme hydrolysed a large number of beta-linked glycoside dimers and oligomers; chromogenic beta-glucosides and beta-fucosides are the preferred substrates, and kinetic analysis indicated that they bind to a common catalytic site. The order of catalytic efficiency was beta 1-3 > beta 1-4 > beta 1-6 and cellotetraose > cellotriose > cellobiose for glucose dimers and oliogomers respectively. The cleavage occurred at the non-reducing end of the oligosaccharide, and the enzyme showed noticeable specificity also for the aglycone part of substrates. From these results the enzyme from S. solfataricus strain MT-4 is defined as a true glycosyl hydrolase with remarkable exo-glucosidase activity and it is designated S beta-gly.
Nucci
R
R
Institute of Protein Biochemistry and Enzymology, Naples, Italy.
Moracci
M
M
Vaccaro
C
C
Vespa
N
N
Rossi
M
M
D002240:Carbohydrate Sequence; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D013379:Substrate Specificity; D016944:Sulfolobus / Q000201:enzymology*
D006026:Glycoside Hydrolases