Talk:Ligand (biochemistry)

Untitled
The second graph is wrong. The curves should be sigmoidal, like in the figure of the article Dose-response relationship.--InfoCan (talk) 15:10, 20 October 2008 (UTC)
 * I agree with InforCan if no compelling argument is offered. Furthermore do molecular biologist/biochemists really use a lowercase "kd"?  As a chemist I follow the convention that all equilibrium constants should represented in the upper case often italicized as in "Kd".  Lowercase is reserved for kinetics so "kd" would the rate at which a substrate dissociates.--128.231.88.7 (talk) 16:01, 22 January 2009 (UTC).

I agree that the second graph was wrong: however, it should not be sigmoidal because the axes are linear-linear; the sigmodial shape will only appear on a log-linear plot. I've now replaced the original image for this page with one properly (I hope) comparing the binding of two ligands with different affinity.(Klbrain)

Ligand
This (here) is how I understand ligand, however, why there are two articles about ligands? What is it, that makes ligand different topic, I see it is defined differently there, however I do not understand the distinction or if there is context dependence of it.. or what .. I would assume the meaning here is more general, can it be understood as primary meaning?--R e o + 02:11, 30 December 2012 (UTC)

Propose merging Protein ligand into this article
I'd like to propose that we merge Protein ligand into this article. Please discuss here. Klortho (talk) 01:46, 25 April 2013 (UTC)

Hormons?
Are hormons considered ligands? Generally they are. And antigens are ligands for their antibodies. The word is used for many types of molecules which bind transporter proteins (or for storage), regulator proteins, antibodies, ect. And in hemoglobin (caption of the first picture) oxygen is the ligand and the hemo is a prosthetic group (not a ligand).--Miguelferig (talk) 00:45, 15 July 2013 (UTC)

Emphasis on small molecules
I removed the wording in the top section stating that ligands are usually small molecules. Aside from the imprecise terminology (what does "usually" mean?), this statement has no evidence to support it. There are thousands of known ligand-receptor interactions involving "large" molecules, including proteins, membrane components, DNA, RNA, bacterial cell wall elements, etc. etc. Yes, there are a large number of naturally-occurring small molecule ligands, not to mention the gigantic chemical libraries synthesized by pharmaceutical companies, but the blanket statement that biochemical ligands are usually small molecules is just incorrect. DadOfBeanAndBug (talk) 13:53, 16 June 2015 (UTC)

Possible typo?
Here is a line in the article: "Non labelled methods such as surface plasmon resonance and dual polarisation interferometry can also quantify the affinity from concentration based assays but also from the kinetics of association and dissociation, ..." What is meant by some methods can also quantify something from A but also from B?李4 (talk) 09:41, 24 June 2015 (UTC)

Undefined Ki in first main section
In the "Receptor/ligand binding affinity" section, in the second paragraph, the sentence "High-affinity ligand binding implies that a relatively low concentration of a ligand is adequate to maximally occupy a ligand-binding site and trigger a physiological response. The lower the Ki concentration is..." introduces but does not define Ki, nor is Ki defined in an earlier section in this article. Perhaps a link to Ki (dissociation constant) can be included, in which case, be consistent and don't say Ki but say Kd (because Kd is used later in this section). That or provide a brief definition of Ki/Kd, and give us some context; the sentence shouldn't just jump right into using the term Ki until it is defined. Sheimanj (talk) 04:36, 26 March 2017 (UTC)

External links modified
Hello fellow Wikipedians,

I have just modified one external link on Ligand (biochemistry). Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
 * Added archive https://web.archive.org/web/20071219185224/http://www.graphpad.com/curvefit/homologous_.htm to http://www.graphpad.com/curvefit/homologous_.htm

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

Cheers.— InternetArchiveBot  (Report bug) 03:45, 23 December 2017 (UTC)

purpose in Biology
This is a rather philosophical point: biology has no purpose. The first sentence of the article states that "a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose." I would like to propose "a ligand is a substance that forms a complex with a biomolecule which results in some form of labor." Labor in this case means anything that consumes energy, like a conformational change, a chemical reaction, a movement etc. --Phacelias (talk) 12:55, 23 January 2019 (UTC)

""Biomacromolecular structures

Biomacromolecules are large biological polymers, such as nucleic acids, proteins, and carbohydrates, that are made up of monomers linked together.

For example, proteins are composed of monomers called amino acids. They are linked together to form a polypeptide chain, which folds into a three dimensional (3D) structure to constitute a functional protein. Often a functional macromolecule is composed of more than one such chain and sometimes requires small molecules to assist in its function.

Smaller molecules such as coenzymes, cofactors, prosthetic groups, lipids, drugs and metal ions because they might interact with and affect these biomacromolecules at the structural level.

When a small molecule binds specifically and reversibly to a biomacromolecule, forming a complex which alters its activity or function, it is called a ligand.

Ligand/small molecule

In the Protein Data Bank, small molecules (low molecular weight organic compounds that are not part of polymers) are frequently associated with biomacromolecules.

Any substance that binds specifically and reversibly to a biomacromolecule to form a larger complex and alters its activity or function is called a ligand. In the Protein Data Bank, drugs, metals, and small molecules are also called ligands.""

Please keep the wording in the opening synopsis to a universally agreed upon definition.

Signed - Humpty Dumpty — Preceding unsigned comment added by 49.185.137.168 (talk) 13:29, 15 May 2022 (UTC)

"Intermolecular interaction"
The affinity does not measure the strength of interactions between a ligand and a protein. In fact, "strength of interactions" is not well defined thermodynamically. Rather, the text should be rewritten to be based on binding equilibria.