sup 19 F NMR investigations of the catalytic mechanism of phosphoglucomutase using fluorinated substrates and inhibitors

Journal Article · Tue Jan 21 04:00:00 EST 1992 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00117a029· OSTI ID:5688036

Percival, M D; Withers, S G ^[1]

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1. Univ. of British Columbia, Vancouver (Canada)

The complexes of phosphoglucomutase with a number of fluorinated substrate analogues have been investigated by {sup 19}F NMR and the effects of the binding of Li{sup +} and Cd{sup +} to these complexes determined. Very large downfield chemical shift changes accompanied binding of the inhibitors 6-deoxy-6-fluoro-{alpha}-D-glucopyranosyl phosphate and {alpha}-glucosyl fluoride 6-phosphate to the phosphoenzyme. Smaller shift changes were observed for ligands substituted with fluorine at other positions. Addition of Li{sup +} to enzyme/fluorinated ligand complexes caused a 10{sup 2}- to 10{sup 3}-fold decrease in ligand dissociation constants as witnessed by the change from intermediate to slow-exchange conditions in the NMR spectra. Measurement of the {sup 19}F NMR spectra of the complexes of the Li{sup +}-enzyme with each of the fluoroglucose 1-phosphates and 6-phosphates has provided some insight into the environment of each of these fluorines in each of the complexes. Results obtained argue strongly against a single sugar binding mode for the glucose 1- and 6-phosphates. Two enzyme-bound species were detected in the {sup 19}F NMR spectra of the complexes formed by reaction of the Cd{sup 2+}-phosphoenzyme complex with the 2- and 3-fluoroglucose phosphates. These are tentatively assigned as the fluoroglucose 1,6-bisphosphate species bound in two different modes to the dephosphoenzyme. The results from this investigation, and those above, are consistent with an exchange type of mechanism for the enzyme in which there are two distinct glucose ring binding sites.

• OSTI ID: 5688036
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 31:2; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACETATES
ALKALI METAL COMPOUNDS
CADMIUM COMPOUNDS
CARBOXYLIC ACID SALTS
CHLORIDES
CHLORINE COMPOUNDS
ENZYME INHIBITORS
ENZYMES
FLUORINE 19
FLUORINE ISOTOPES
HALIDES
HALOGEN COMPOUNDS
ISOTOPES
LIGHT NUCLEI
LITHIUM CHLORIDES
LITHIUM COMPOUNDS
LITHIUM HALIDES
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXIDOREDUCTASES
PROTEINS
RESONANCE
STABLE ISOTOPES