METABOLIC NONEQUIVALENCE OF THE TWO GLUCOSE MOIETIES OF CELLOBIOSE IN CELLVIBRIO GILVUS

Abstract

Cellobiose was synthesized in 40% yield with uniform C14 labeling in the reducing glucose moiety and no label in the nonreducing glucosyl. Resting-cell suspensions of C. gilvus respiring the labeled cellobiose derived approximately 80% of their respiratory CO2 from the reducing glucosyl and 20% from the nonreducing glucose. Analysis of isotope content in CO2 from cells respiring a mixture of labeled cellobiose and unlabeled glucose confirmed that the glucose-1-phosphate produced from phosphorolysis of cellobiose is less extensively converted to CO2 than is either the glucose released by phosphorolysis of cellobiose or glucose absorbed from the medium. In crude cell extracts, release of glucose from cellobiose was shown to be Pj-depen-dent, the pH optimum of cellobiose phosphorylase being 6.2.