Talk:Michaelis–Menten kinetics

message: I changed the explanation of the quasi-steady-state approximation from:
:The current derivation, based on the quasi steady state approximation (which asserts that the concentrations of the intermediate complexes initially change so as to approach the set in phase space where their rate of change is zero)
to
:The current derivation, based on the quasi steady state approximation (that the concentrations of the intermediate complexes remain constant)
The derivation is based on the assumption that the concentrations do not change, no more, no less.  The discussion about the representation in phase space might indeed be a more accurate and complete description of the quasi-steady-state approximation, but at that point in the article it's just confusing to non-specialists. --Slashme (talk) 13:43, 5 June 2008 (UTC)
replies: text: Nice, but it should also be explained that the equation always breaks down at low concentration. I.e., at very small [S], substrate binding is always rate limiting, so V approaches k_1 [S], but that's not what the MM equation approaches. I don't see the merit of considering phase space for that matter. Physicsjock (talk) 17:22, 16 July 2008 (UTC)
thread_title:  Phase space 

message: Both TeX and non-TeX math notation conventions were somewhat extensively disregarded in this article; I've (mostly?) fixed that.  See Wikipedia:Manual of Style (mathematics).  In particular, I found this:
: 
 E + S
  \begin{matrix}
    k_1 \\
    \longrightarrow \\
    \longleftarrow  \\
    k_{\textrm{-}1}
  \end{matrix}
 ES
  \begin{matrix}
    k_2 \\
    \longrightarrow\\
    \ 
  \end{matrix}
 E + P
: 
and I changed it to this:
: 
: 
 E + S \overset{k_1}{\underset{k_{-1}}{\begin{smallmatrix} \displaystyle \longrightarrow \\ \displaystyle \longleftarrow \end{smallmatrix}}}
 ES
   \overset{k_2}
    {\longrightarrow}
 E + P
: 
Note: In non-TeX notation, italicize variables, but NOT digits and NOT parentheses or other punctuation.  Put a space before and after "+", "=", etc. (make in non-breakable when prudent, especially with plus, minus, etc.).  In TeX that doesn't matter; the software takes care of it.  In non-TeX notation, a minus sign is not just a hyphen:
: 
: 5 - 3
: 5 − 3
: 
Michael Hardy (talk) 15:22, 14 August 2008 (UTC)
thread_title:  Mathematical notation 

message: I tried to clean up the derivation of the Michaelis-Menten approximation,
:  [ES] = \frac{1}{1 + \frac{K_m}{[S]}} , 
from the quasi-steady-state assumption (QSSA)
:  \frac{d[ES]}{dt} = 0 . 
It should read much more smoothly now. I also added a short discussion of the mathematical limitations of the QSSA (and therefore also of the Michaelis-Menten kinetics) & a reference to the best reference on the subject. Finally, I tried to uniformize the citation style a bit, as it was a huge mess... Athenray (talk) 20:50, 5 November 2008 (UTC)
thread_title:  Mathematical derivations 

message: I changed the equation for Km. It has to be \frac{k_{-1}+k_2}{k_1} instead of  \frac{k_{-1}+k_2}{k_{-1}}. Just solve the equations yourself or look into a textbook to check this.  —Preceding unsigned comment added by 129.132.49.164 (talk) 08:42, 11 January 2009 (UTC)
replies: text: This is correct, there was a typo. Thanks for correcting it. --hroest 21:46, 17 March 2009 (UTC)

text: Unsigned user is correct. I suggest to add the adjective "apparent" before "affinity", then develop why Km is an affinity constant only in the particular case where k_2\ll k_{-1}, maybe in a subsection entitled "The meaning of the Michaelis constant" ? The section Enzyme_kinetics#Michaelis-Menten_kinetics is clearer about that point, although the use of "quickly" in "The two most important kinetic properties of an enzyme are how quickly the enzyme becomes saturated with a particular substrate, and the maximum rate it can achieve." (Enzyme kinetics#General_principles) is very misleading... I have suggested a change on the corresponding dicussion page. Lewisiscrazy (talk) 08:54, 21 January 2018 (UTC)
thread_title:  Km 

message: It would be nice if the limitations were quantified and bounded. For example, Olsen's work is cited when making the point that diffusion is a problem in the cell but the citer didn't include any numbers. (BTW, my reading of Olsen's abstract is that Michaelis-Menten kinetics held up fine.)  —Preceding unsigned comment added by Richmc (talk • contribs) 00:34, 15 January 2009 (UTC)
replies: text: What do you mean with 'quantified and bounded'? I guess you mean stating the error (or estimates thereof)? I can do this for the mathematical limitations if needed.Athenray (talk) 17:36, 13 February 2009 (UTC)
thread_title:  Limitations 

message: I have twice undone additions of information on "optimal uptake kinetics", most recently with this edit. I don't feel that this is the appropriate place for seven paragraphs about this theory, but would appreciate others' views on this. U+003F? 18:53, 29 October 2011 (UTC)
replies: text: I agree that the "optimal uptake kinetics" section is not appropriate for this article. The application of the MM equation to the "nitrate uptake by phytoplankton in the ocean" is way too specialized for this article – and is probably unsuitable for any wikipedia article -  secondary sources would be required. Aa77zz (talk) 10:20, 30 October 2011 (UTC)
thread_title:  Optimal uptake kinetics 

message: I think the next text isn't right, the term should be turnover frequency and not turnover number. Number is the maximum number of reactions an enzyme can do before it is degraded. The term should be turnover frequency as it is a value of the number of reactions per unit time. I haven't corrected yet, and wait for people to agree and change it (perhaps i'm wrong)
"the turnover number, is the maximum number of substrate molecules converted to product per enzyme molecule per second."  — Preceding unsigned comment added by 77.173.73.102 (talk) 23:13, 16 December 2013 (UTC)
thread_title:  Turnover number and turnover frequency 

message: Substituted at 23:56, 29 April 2016 (UTC)
thread_title: Assessment comment

message: :
:
:I am wondering why the five edits by two Hunter college students were deleted again by one of them? In my opinion they were useful and well-sourced additions to the article, which I would have restored if they had been deleted by someone else. Are either or both of these two editors interested in restoring all or part of the deleted text? Dirac66 (talk) 02:02, 18 December 2017 (UTC)
thread_title:  Unexplained deletion by author and classmate? 

message: Apparently somebody thought that the way to put a period at the end of a sentence is this:
:
\begin{align}
(k_r + k_\mathrm{cat}) [\ce{ES}] &= k_f [\ce S] ([\ce E]_0 - [\ce{ES}]) \\[4pt]
&= k_f [\ce S] [\ce E]_0 - k_f [\ce S] [\ce{ES}]
\end{align}
.
That is silly. I changed it to this:
:
\begin{align}
(k_r + k_\mathrm{cat}) [\ce{ES}] &= k_f [\ce S] ([\ce E]_0 - [\ce{ES}]) \\[4pt]
&= k_f [\ce S] [\ce E]_0 - k_f [\ce S] [\ce{ES}].
\end{align}
Michael Hardy (talk) 18:02, 18 March 2019 (UTC)
replies: text: It's rarely necessary or helpful to put punctuation in equations at all. I would omit the full stop. Athel cb (talk) 18:52, 1 April 2023 (UTC)
thread_title:  Common sense in punctuation 

message: It seems as if the equation mentioned in the lead is commonly referred to as the Briggs-Haldane equation (and not the Michaelis–Menten equation). 
If we want to have the Michaelis–Menten equation in the lead, then we have to change the Km to Kd. The Michaelis–Menten equation assumes equilibrium, while the Briggs-Haldane equation assumes a steady state. 81.191.81.174 (talk) 18:14, 7 December 2022 (UTC)
replies: text: The mechanism proposed by Michaelis and Menten assumed equilibrium, yes, but today nearly everyone takes the Michaelis–Menten equation to be the form derived by Briggs and Haldane. Athel cb (talk) 18:48, 1 April 2023 (UTC)
thread_title:  Michaelis–Menten equation vs Briggs-Haldane equation 

message: I find this subsection too advanced in style for the general level of the article. I would prefer a dumbed-down version that gives appropriate references to Schnell. Athel cb (talk) 18:56, 1 April 2023 (UTC)
thread_title: Assumptions and limitations

message: Is it misleading to use "Michaelis–Menten plot" for a diagram of v over a? After all, such a plot would show data fitted to the Michaelis-Menten equation, so the name matches quite well. 
V was plotted over log a in the original paper, yes it's true. This way of plotting is not used anymore for this data, also true. Unnecessary techniques should become forgotten over time. There is enough other information on the Michaelis-Menten equation relevant today that we should care about. The section "Michaelis–Menten plot" might be dispensable. 2003:F8:3F1D:1BC8:DC57:32A4:5900:6ED2 (talk) 19:59, 5 February 2024 (UTC)
thread_title:  "Michaelis–Menten plot"