Question

1. List positive and negative effectors for oxygen binding to hemoglobin.
2. explain cooperative binding using hemoglobin as an example.
3. Correlate the NCI involved in stabilizing Hb’s and Mb’s structures.

please answer all

Answer 1

1) Hb molecule is made up of 4 subunits, 2 alpha and 2 beta. Each subunit contains one heme molecules this 4 subunits contains 4 heme and transport 4 molecules of oxygen. HB e ist in two form, T ( tense ) form unable to transport oxygen, T form ( relaxed) transport oxygen.

Various molecules affect conversion of R to T form or vice versa, known as allosteric modulators.

Positive modulators- convert T to R form , help in tranport of oxygen, oxygen molecules act as a positive allosteric modulators

Negative allosteric modulators- convert R to T form, help in release of oxygen. Includes H+ , increase pCo2, CL- , 2 ,3 BPG etc.

2) conversion of T form of Hb in to R form occurs due to cooperative binding phenomenon. In T form , subunits movements are restricted due to presence of salt brides between alpha and beta subunits. Thus unable to transport oxygen.

As one molecule of oxygen binds to one subunit it leads to break some some of the bonds and also facilitate binding of other oxygen molecule. When second molecule of oxygen binds to T form , conversion of more oxygen to R form . And more affinity to coming third oxygen molecule. Similar way last oxygen molecule has highest affinity to R molecule. This shows binding of one molecule to Hb , increase affinity to oxygen to other molecule known as cooperative binding of oxygen. This has been explained in attached image below