Investigation of the Pre-Steady-State Kinetics of Fructose Bisphosphatase by Employment of an Indicator Method

Patricia A. Benkovic, Mohammed Hegazi, Brian A. Cunningham, Stephen Benkovic

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Abstract

The pre-steady-state kinetics for the hydrolysis of fructose 1, 6-bisphosphate by rabbit liver fructose bisphosphatase have been investigated by stopped-flow kinetics utilizing an acid-base indicator method that permits the continuous monitoring of the inorganic phosphate product. The reaction sequence is characterized by two successive first-order steps followed by establishment of the steady-state rate. The first exponential process results from a conformational change in the protein that is dye sensitive owing to a perturbation of an acidic residue on the protein. A second process reflects the rapid initial turnover of all four subunits of the enzyme with the concomitant release of inorganic phosphate followed by the rate-limiting step of the catalytic cycle. This latter step may involve a product release (fructose 6-phosphate) or a second conformational change. The catalytic cycle ends with decay of the enzyme to its initial unreactive resting state.

Original languageEnglish (US)
Pages (from-to)830-835
Number of pages6
JournalBiochemistry
Volume18
Issue number5
DOIs
StatePublished - Jan 1 1979

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All Science Journal Classification (ASJC) codes

  • Biochemistry

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