Russell PJ, Williams A, Austin TA. Inhibition of rabbit muscle isozymes by vitamin C.
JOURNAL OF ENZYME INHIBITION 2000;
15:283-96. [PMID:
10811033 DOI:
10.3109/14756360009040689]
[Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The ability of vitamins C, E and K to inhibit enzymes directly has been investigated. It was found that vitamin E and some analogs and menadione (vitamin K3) inhibited several enzymes irreversibility at concentrations below one millimolar. Ascorbate inhibits rabbit muscle 6-phosphofructokinase (MPFK-1; EC 2.7.1.11), muscle type LDH (EC 1.1.1.27), and muscle AK (EC 2.7.4.3) at low concentrations that do not inhibit equivalent liver isozymes. Ascorbate Ki values for muscle-type LDH and heart-type LDH isozymes are 0.007 and 3 mM, respectively. The ascorbate Ki value for rabbit skeletal muscle PFK-1 is 0.16 mM; liver PFK-I is not inhibited by ascorbate. Dehydroascorbate does not inhibit any enzyme at ascorbate concentrations normally found in cells. All ascorbate inhibitions are completely reactivated or nearly so by L-ascorbate oxidase, CYS, GSH, or DTT. We propose a hypothesis that ascorbate facilitates glycogen storage in muscle by inhibiting glycolysis. The relationship between ascorbate metabolism and diabetes is discussed.
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