Allosteric interactions of glycogen phosphorylase b. A crystallographic study of glucose 6-phosphate and inorganic phosphate binding to di-imidate-cross-linked phosphorylase b

Oligosaccharide binding to glycogen phosphorylase b.

ORDERED MECHANISM OF BINDING OF PHOSPHORYLASE KINASE AND GLYCOGEN PHOSPHORYLASE b TO GLYCOGEN

The kinetics of the interaction of rabbit skeletal muscle phosphorylase kinase with glycogen has been studied using turbidimetric method (40 mM Hepes, pH 6.8, and 8.2; 20◦C). The binding of phosphorylase kinase with glycogen occurs only in the presence of Ca and Mg . According to the kinetic data, phosphorylase b favors the binding of phosphorylase kinase with glycogen. This conclusion is suppo...

Probing the ionization state of substrate alpha-D-glucopyranosyl phosphate bound to glycogen phosphorylase b.

The ionization state of the substrate alpha-D-glucopyranosyl phosphate bound at the active site of glycogen phosphorylase has been probed by a number of techniques. Values of Ki determined for a series of substrate analogue inhibitors in which the phosphate moiety bears differing charges suggest that the enzyme will bind both the monoanionic and dianionic substrates with approximately equal aff...

Glucose 6-phosphate regulates hepatic glycogenolysis through inactivation of phosphorylase.

High glucose concentration suppresses hepatic glycogenolysis by allosteric inhibition and dephosphorylation (inactivation) of phosphorylase-a. The latter effect is attributed to a direct effect of glucose on the conformation of phosphorylase-a. Although glucose-6-phosphate (G6P), like glucose, stimulates dephosphorylation of phosphorylase-a by phosphorylase phosphatase, its physiological role i...

Location of pyridoxal phosphate in glycogen phosphorylase a.

The pyridoxal 5'-phosphate cofactor of glycogen phosphorylase a (1,4-alpha-D-glucan:orthophosphate alpha-glucosyltransferase, EC2.4.1.1.) has been positioned on the protomer with x-ray diffraction data, chemical markers, and sequence information. The electron density was computed from 3.0-A resolution phases calculated from four heavy-atom derivatives. The cofactor is buried inside the protomer...