Talk:Affinity label

affinity label targets
I am pretty sure I've seen affinity labels for non-enzymatic proteins such as hemoglobin, hormone receptors, and antibodies. Perhaps they are called something different but I don't think I've noticed that. Could it be that any protein (or maybe any macromolecule?) could be affinity labeled? Just has to have a binding site for something? I don't know for sure.LLMHoopes (talk) 18:43, 12 August 2018 (UTC)

After working with the sandbox related to this article written by another Fellow I still think it should be broadened in scope beyond just enzymes. Also relevant to that argument (see above) is the last sentence which implies that substrate binding studies are all these are good for. Certainly a lot of affinity labels are used to track a protein intracellularly or through the bod`` and that probably needs to be included here.LLMHoopes (talk) 04:23, 17 August 2018 (UTC)

These references are to affinity labels for non-enzymes; one is for a ribozyme, one for a carrier protein, and one for antibodies. M Kavanaugh, DTB Shih, and RT Jones. (1988) “Affinity labeling of hemoglobin with 4,4'-diisothiocyanostilbene-2,2'-disulfonate: covalent cross-linking in the 2,3-diphosphoglycerate binding site” Biochemistry 27 (5): 1804–1808. DOI: 10.1021/bi00405a062 Covers affinity labeling of hemoglobin, a carrier rather than an enzyme. L Wolsy, H Metzger, and SJ Singer. (1962)Affinity labeling—a general method for labeling antibody and enzyme molecules. Biochemistry 1 (6):1031-1039. DOI: 10.1021/bi00912a013  Covers affinity labeling of antibodies which are not enzymes.

P Greenwell, RJ Harris, and RH Symons. (1974) “Affinity labeling of 23s Ribosomal RNA in the active center of Escherichia coli peptidyl transferase.” European Journal of Biochemistry 49: 539-554. This is about a ribozyme rather than an enzyme. LLMHoopes (talk) 17:36, 20 August 2018 (UTC)

Re-affinity labeling
This is an interesting article, but, how is this affinity labeling different from “affinity” in chromatography? I presume that, affinity labeling is the same in principle, whether it is about enzymes, proteins, salts, or physical substrates. Martins Emeje (talk) 16:28, 22 August 2018 (UTC)

Response of other molecules that can be affinity labeled
Thanks for your comments. Ribozymes and antibodies can certainly be affinity labeled due to their active site and I have included this. However, this term has fallen out of use for these substrates as they did not find good use. The papers you have cited are ancient and definitions evolve. For example, see the cited discussion on the definition of a quiescent label in both Fast papers. Non-enzyme proteins can generally not be affinity labeled as they have no active site. However, if the protein binds a molecule in a defined pocket it could be affinity labeled. Jlf3756 (talk) 01:47, 5 September 2018 (UTC)