Can random and ordered sequential mechanisms be descern by Lineweaver-Burk plot? Why or why not? Because for orederd sequential mechanism I got different LB plot depending on which substrate is held constant (when A, which binds first to the enzyme, is held constant lines for different concentrations of A in Lineweaver-Burk plot have same intercept 1/Vmax). And how are they differed based on product inhibition studies?
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Edit: cite corrected.
The authors of the study cited below [1] indicate that distinguishing ordered sequential from random sequential mechanisms can be done using "dead-end" substrates that do not go on to form products. Lineweaver-Burke plots of the data should allow us to distinguish between the two cases.
The artificial substrate, a cognate of one of the two natural substrates, is unable to bind to the free enzyme, but is able to bind if the enzyme is already bound to the other substrate. This is uncompetitive inhibition, which results in parallel lines in the Lineweaver-Burke plots; and we can infer that the artificial substrate's cognate binds only after the other substrate is bound.
Using this approach the authors were able to demonstrate both the ordered binding of substrates and ordered release of products. Lineweaver-Burke plots, shown in the paper, helped them distinguish between sequential/ordered and sequential/random.
I assume the language in this article is standard and correct. That said, the complexity of enzyme mechanisms are sometimes belied by classical mechanistic categories, and descriptions of the mechanism are key.
[1] Analysis of the kinetic mechanism of recombinant human isoprenylcysteine carboxylmethyltransferase (Icmt),Baron and Casey, Jan. 2005, BMC Biochemistry 5(1):19,DOI: 10.1186/1471-2091-5-19.
