Rigorous determination of the Hill coefficient of non-Michaelian substrate-inhibited enzymes.
The Hill coefficient (n), the max. velocity (VM) and the dissociation constants of the competent enzyme-substrate complex (Ks) and of the inhibitory bindings of substrate to both pure enzyme (Kse) and to ES (Kses) can be determined using a particular property of the representative equation. Choosing successive pairs of substrate concns (Si, Sj) in such a way as Si.Sj = 1, and plotting Sj-1 versus Si-1 gives a family of straight lines whose slopes are: b = Ks.kses, i.e.b = Sm2n, independent of Si, Sj. Then: n = Lnb/2 LnSm, where Sm corresponds to vm, maximum value of v on the curve. All of the other parameters can be calculated from the value of n.
Bounias
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INRA, University of Avignon, Laboratory of Biochemistry, Montfavet, France.
D000494:Allosteric Regulation; D004791:Enzyme Inhibitors / Q000378:metabolism*; D004798:Enzymes / Q000378:metabolism*; D007700:Kinetics; D008433:Mathematics; D008956:Models, Chemical; D013379:Substrate Specificity
D004791:Enzyme Inhibitors; D004798:Enzymes