**************** The 10th., Lab Seminar ****************************

Date: Thu, February 18, 2009  PM 1:30-

Place: No.616 Seminar room
　　　　　　 Graduate School of Information Science

Speaker: Masayoshi Takayanagi

Title: Evolution of Allosteric Models for Hemoglobin
W.A. Eaton et al., IUBMB Life, 59 (2007) 586.

Abstract:
 We compare various allosteric models that have been proposed to
explain cooperative oxygen binding to hemoglobin, including the
two-state allosteric model of Monod, Wyman, and Changeux
(MWC), the Cooperon model of Brunori, the model of Szabo and
Karplus (SK) based on the stereochemical mechanism of Perutz, the
generalization of the SK model by Lee and Karplus (SKL), and the
Tertiary Two-State (TTS) model of Henry, Bettati, Hofrichter and
Eaton. The preponderance of experimental evidence favors the TTS
model which postulates an equilibrium between high (r)- and low (t)-
affinity tertiary conformations that are present in both the T and R
quaternary structures. Cooperative oxygenation in this model arises
from the shift of T to R, as in MWC, but with a significant
population of both r and t conformations in the liganded T and in the
unliganded R quaternary structures. The TTS model may be
considered a combination of the SK and SKL models, and these
models provide a framework for a structural interpretation of the
TTS parameters.

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