Poyart C, Schaad O, Kister J, Galacteros F, Edelstein S J, Blouquit Y, Arous N
Institut National de la Santé et de la Recherche Médicale, Faculté de Médecine Paris-Sud, France.
Eur J Biochem. 1990 Dec 12;194(2):343-8. doi: 10.1111/j.1432-1033.1990.tb15624.x.
Oxygen equilibrium studies of purified hemoglobin Saint Mandé (Hb SM) [beta 102 (G4) Asn----Tyr] reveal a decreased oxygen affinity and cooperativity but to a lesser extent than found for Hb Kansas (beta 102 Thr). The low affinity of Hb SM depends on environmental conditions: eliminating chloride or raising the pH greatly elevated the ratio of p50 of Hb SM to that of Hb A. The alkaline Bohr effect is reduced by about 40%. The effects of anions (chloride, organophosphates) binding to deoxy Hb SM are also reduced. These data indicate that the functional properties of Hb SM are intermediary between Hb A and Hb Kansas. In addition, molecular graphics modeling of Hb SM in the oxy and deoxy structures indicate the possibility of a new hydrogen bond in the T state between beta(1)102 Tyr and alpha(2)42 Tyr. Stabilisation of the T state in this manner is a plausible explanation for several of the effects observed.
