m25

May 28, 2014
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When allosteric effectors bind to allosteric sites on enzyme, are they binding covalently or noncovalently, or can it bind either way?
 

StIGMA

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When allosteric effectors bind to allosteric sites on enzyme, are they binding covalently or noncovalently, or can it bind either way?
It is a noncovalent (and therefore reversible). Remember there are no absolutes in biology as you seem to want to believe- so generally think of it as noncovalent.

In cell biology, "binding" of one molecule to another is nearly always non-covalent. An exception is enzymatic reactions where transient intermediates form.

However, certain protein modifications, which can occur on allosteric sites, are covalent modifications (such as phosphorylation); this would not be referred to as "binding" of phosphate to the protein- it would be called a covalent modification or post-translational modification. Protein modifications (ie: post-translational modifications) are not, strictly speaking, considered allosteric effectors (which refers to diffusible molecules that non-covalently associate with a site on the protein that is NOT the active site to modify the enzymatic activity of that protein).

Simple, huh?
 
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