Hemoglobin subunit motions

FIGURE 15.31 Subunit motion in hemoglobin when the molecule goes from the (a) deoxy to the (b) oxy form. (Irving G sj... 

Fig. 2. Quaternary structural transition in hemoglobin. (A) Subunit motion of hemoglobin in going from the deoxy (or T conformation) to the oxy (or R conformation) state (B) side views of deoxy and oxy states of hemoglobin. In oxy-Hb, the oiiPi dimer is rotated 15° relative to the a2p2 dimer. [Adapted from Dickerson and Geis (1983) illustration copyright by I. Geis],...

Albaiii, J., Alpert, B., Krajcarski, D. and Szabo, A. G, 1985, A fluorescence decay time study of tryptophan in isolated hemoglobin subunits. FEBS Letters. 182, 302-304. Albani, J. and Alpert, B, 1986, Porphyrin motions in the myoglobin heme-pocket. Chemical Physical Letters. 131, 147-152. 

Relative motion of the subunits of hemoglobin upon oxygenation and deoxygenation. 

The binding of oxygen to the deoxy form of hemoglobin (deoxyhemoglobin) causes a reduction in diameter of the iron atom which can then relax into the plane of the porphyrin ring. This motion is transferred to the polypeptide through the proximal histidine and eventually causes sliding of the subunits across one an-... 

---