Talk:Non-competitive inhibition

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Wiki Education Foundation-supported course assignment

This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Student editor(s): Huff59, Allisonbcookie, Mbunten, NiceGuyLEddie, ChristinaEllis0604, TBOW, Kjean1221, AMars1997.

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organophosphate insecticides are non-competitive at active site, right?

I'm not sure that it is correct to call non competitive inhibition allosteric. Certainly they are similar with regard to the inhibitor (and activator in the case of allosteric enzymes) binding to a site other than the active site. however, allosteric mechanisms will change the Km whereas non competitive do not change the km. They are different classes of inhibition by definition. David D. (Talk) 04:48, 30 August 2005 (UTC)[reply]

Confusion

There are some discrepancies in the entries about inhibition, causing great (at least to me) confusion: My book (Lehningers principles of biochemistry) state that a mixed inhibitor has been classically defined a noncompetitive inhibitior. Here there are two diffrent entries. Could anyone clariffy? —Preceding unsigned comment added by Leonidaslundell (talk • contribs)

Many text books have it wrong. By definition a noncompetitive inhibitor changes the Vmax, not the Km, and is reversible. Mixed inhibitors typically cause changes to an enzymes Vmax and Km. In fact, there are very few examples of non-competitive inhibitors. As far as i can tell the only reason they are useful with regard to text books is to contrast with competitive inhibitors that change the Km but not the Vmax (exact opposite of non-competitive). Suicide inhibitors are similar to noncompetitive but the fail on the important criteria of being reversible. I suspect what Lehninger is tacitly admiting is that there are no real noncompetitive inhibitors and the closest are mixed inhibitors that have very subtle changes in Km but large changes in Vmax. A better book to read up on this stuff is Biochemical Calculations by Irwin H. Segal. I hope this helps David D. (Talk) 14:58, 15 September 2006 (UTC)[reply]

Wrong approach

It is wrong to define inhibition types based on hypothetical mechanisms. The fact is that non-competitive inhibition is any type of inhibition that causes the apparent limiting rate (Vmax) to decrease without affecting Km. Whether this happens through binding to some other site, or by changing conformation, or by altering electrostatic distribituin, etc. is irrelevant. This article is damaging to education by promoting an erroneous concept. (Yes, the mechanism proposed in the article could lead to non-competitive inhibition but it is a special case) —Preceding unsigned comment added by 86.133.61.88 (talk) 09:02, 26 September 2010 (UTC)[reply]

The purpose of this comment is to emphasize the importance of the previous three comments.

Two sentences that appear in the article contradict each other. The first of those two sentences is the first sentence of the article, which states: "NON-COMPETITIVE INHIBITION is a type of enzyme inhibition [1] where the inhibitor reduces the activity of the enzyme, by binding not to the active site on the enzyme, but to a different site." That sentence is followed with "[1]", which appears in superscript. Reference [1], listed at the end of the article, is Berg, Jeremy M.; Tymoczko, John L.; Stryer, Lubert [3] (2007) _Biochemistry_ (6 ed.), New York [4]: WH Freeman & Co., ISBN [5] 0-7167-6766-X [6]. The second of those two sentences appears under the heading "Mechanism" and states: "The most common mechanism of non-competitive inhibition involves reversible binding of the inhibitor to an allosteric site [7], but it is possible for the inhibitor to operate via other means including direct binding to the active site."

That the second sentence is correct is supported by data from the article "Exosites Determine Macromolecular Substrate Recognition by Prothrombinase" by S. Krishnaswamy and A. Betz, which was published in Biochemistry 1997, 36, 12080-12086. — Preceding unsigned comment added by Jwf6 (talk • contribs) 19:47, 22 January 2012 (UTC)[reply]

Possibly Adding History of Non-competitive inhibition

Our group was assigned to add a history section to non-competitive inhibition. We are looking at: what enzyme the founders were using when they discovered it, the founders along with a bit on their early life, if it was discovered during a Ph.D thesis, and what experiment they were performing to discover it. We believe that history is appreciation. Knowing how something is discovered, when and for what reason could aid future scientists to possibly use in their research. Allisonbcookie (talk) 23:28, 9 October 2017 (UTC) Kade, Mary, Eduard[reply]

Editing Mechanism Section

Our group was assigned the mechanism section of non-competitive inhibition. We intend to add practical examples of non-competitive inhibition, distinguish the difference between non-competitive and competitive inhibition, and a description of the kinetics of non-competitive inhibition in terms of Km and Vmax. AMars1997 (talk) 01:28, 13 October 2017 (UTC), Tyler B, Christina E, and Kelsey H[reply]

The last sentence in the mechanism section is incredibly unclear: "Non-competitive inhibition differs from uncompetitive inhibition in that it still allows the substrate to bind to the enzyme-inhibitor complex and form an enzyme-substrate-inhibitor complex, this is not true in uncompetitive inhibition, it prevents the substrate from binding to the enzyme inhibitor through conformational change upon allosteric binding." First of all, the grammar obscures the meaning - would recommend adding a period after "enzyme-substrate-inhibitor complex" and starting a new sentence with "This..." Second, what is the "it" that prevents substrate from binding to the "enzyme inhibitor." Third, why would the substrate bind to the "enzyme inhibitor"? The substrate binds enzyme. I would recommend a sentence similar to the following: "This is not true in uncompetitive inhibition, in which the inhibitors binds to and stabilizes the enzyme-substrate complex, increasing affinity of enzyme for substrate but impeding product formation." [User:Charliebby] 17:10, 15 October 2021 (PDT), Charlie H