alpha-Glucan phosphorylases catalyze the glucosyl transfer from alpha-D-glucosyl fluoride to oligosaccharides.
Regulated and nonregulated phosphorylases were found to catalyze in a slow, orthophosphate dependent reaction the direct transfer of the glucosyl residue from alpha-D-glucosyl fluoride to an oligosaccharide primer. The enzyme catalyzed formation of the glucosyl residue requires stereospecific protonation of alpha-D-glucosyl fluoride by a Brønstedt acid. The results are interpreted by a mechanism whereby phosphate acts as a proton shuttle and the cofactor pyridoxal 5'-phosphate is required to promote the acid-base function of phosphate.
D000818:Animals; D004926:Escherichia coli / Q000201:enzymology; D005947:Glucose / Q000031:analogs & derivatives* / Q000378:metabolism; D009132:Muscles / Q000201:enzymology; D009844:Oligosaccharides / Q000378:metabolism*; D006005:Phosphorylases / Q000378:metabolism*; D010944:Plants / Q000201:enzymology; D011817:Rabbits
D009844:Oligosaccharides; C030364:glucosyl fluoride; D006005:Phosphorylases; D005947:Glucose