Heterotropic vs Homotropic effectors in biochemistry

Homotropic
A homotropic allosteric modulator is a substrate for its target enzyme, as well as a regulatory molecule of the enzyme's activity. It is typically an activator of the enzyme[1]. For example, O2 and CO are homotropic allosteric modulators of hemoglobin. Likewise, in IMP/GMP specific 5' nucleotidase, binding of one GMP molecule to a single subunit of the tetrameric enzyme leads to increased affinity for GMP by the subsequent subunits as revealed by sigmoidal substrate versus velocity plots[1].
Heterotropic
A heterotropic allosteric modulator is a regulatory molecule that is not the enzyme's substrate. It may be either an activator or an inhibitor of the enzyme. For example, H+, CO2, and 2,3-bisphosphoglycerate are heterotropic allosteric modulators of hemoglobin.[12] Once again, in IMP/GMP specific 5' nucleotidase, binding of GTP molecule at the dimer interface in the tetrameric enzyme leads to increased affinity for substrate GMP at the active site indicating towards K-type heterotropic allosteric activation[1].
As has been amply highlighted above, some allosteric proteins can be regulated by both their substrates and other molecules. Such proteins are capable of both homotropic and heterotropic interactions[1].

[@dengepoz320]

Bro seems like they are the same concept with competitive and non competitive inhibition

[@mustang8206]

Thumb in the loop. 3 red lights

[@yongsooyuk2489]

Thanks dude this 1 minute video really explained something way better than my prof's 5 minute all over the place needless explainations

[@medaphysicsrepository2639]

Thanks for being kind and leaving a comment

[@lananhnguyen7415]

Thank you. It’s a very nice and concise explanation.

[@medaphysicsrepository2639]

Thanks for being kind and leaving a comment

[@조준우-m4y]

Thank you nice video^^ i really appreciate

[@medaphysicsrepository2639]

Glad you found it helpful and were kind enough to leave a comment

[@sarki-m3q]

Thank you. The transcript was helpful 👏

[@medaphysicsrepository2639]

Thanks for your comment! let me know if you have any questions!

[@blaaaah970]

THANK YOU!

[@medaphysicsrepository2639]

thanks for being kind and leaving a comment, let me know if you have any questions!

[@King-qr1ck]

thanks man appreciate it btw what does r state means

[@medaphysicsrepository2639]

R means its the catalytically active state ie the conformation needed to for the enzyme to do its job. Thanks for asking the question, let me know if you have any more!

[@caitygart]

Thank you for this video, it was very helpful.

[@medaphysicsrepository2639]

LOL most polite comment on the internet. let me know if you have any questions or need any private tutoring

[@caitygart]

@@medaphysicsrepository2639 Thank you very much. I try to be sure to leave comments on all of the videos I find that help me understand difficult University concepts so that creators and teachers like yourself understand the impact they really make, and thanks to you I know the difference between heterotropic and homotropic effectors and was prepared for (part) of my biochemistry exam on Friday :). I will be sure to keep track of your videos as I progress through my class. Cheers!

[@medaphysicsrepository2639]

@@caitygart Always nice to hear feedback, be sure to let me know if a video doesnt explain something well enough though!

[@nemoelk5230]

Would H+ be considered a heterotropic effector?

[@medaphysicsrepository2639]

Yes it is,
If i may give some unsolicited advice: most professors will undoubtedly ask you to identify the dissociation curve of hemoglobin under normal physiological conditions, increased pC02, decreased pH and fetal hemoglobin on a quiz, exam, or etc. So if you are studying biochem for an exam id recommend knowing that
ps
I have a video on the Bhor effect specifically if youd like to watch it here: ua-cam.com/video/-i2PCLGUXKc/v-deo.html

[@nemoelk5230]

Thomas Underhill i see so what would calcium, glyphosate and oxygen be considered?

[@medaphysicsrepository2639]

Tell me what you think ?

[@raoulfulgos8536]

@@medaphysicsrepository2639 homotropic?

[@nitajusufi7836]

thank you

[@medaphysicsrepository2639]

thanks for being kind

[@chloekwon6523]

If Homotropic allosteric activator binds to the "active site," why is it called an "allosteric" activator? Isn't "allosteric" something that does not bind to the active site?

[@medaphysicsrepository2639]

It does not bind to the "active site" it binds to an allosteric site, you are correct on the definitions the greek word 'allos' literally means 'other'

[@chloekwon6523]

But isn’t substrate something that binds to the active site, not allosteric site? And homotropic allosteric activator binds to the active site as a substrate ? (I.e. F6P is a homotropic allosteric activator that binds to the active site of PFK)

[@medaphysicsrepository2639]

@@chloekwon6523 F6P is the substrate of PFK, so it would be homotropic and not hetero
in general (some exceptions to this bc its an arbitrary man made system)
homo = substrates and similar compoounds
hetero = allosteric

[@chloekwon6523]

@@medaphysicsrepository2639 right. bc F6P is a substrate, it binds to the active site, but then why is it called homotropic “allosteric” regulator? I understand that ot’s homotropic but i’m confused why it’s named “allosreric” even though it binds to the active site not the allosteric site. And tysm for your answer!

[@medaphysicsrepository2639]

@@chloekwon6523 Sorry I just now realized what your question is asking, "homotropic allosteric regulator" is not a term I am familiarized with, it could be a new term or an old term that wasnt used to describe enzyme kinetics when I was in school. Keep in mind, before we had things like synchrotron radiation and 1000000 different folding modules we based these definitions on how they effected the kinetics of the curve. These curves are merely describing what is going on, it is not explaining what is going on.
here is a video where I talk about the difference between mechanistic models and probabilistic models
ua-cam.com/video/SNGdjEU9WWc/v-deo.html
TLDR hetero and homotropic is classified by the shape of the curve and not necessarily the enzyme's chemical structure