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Modification of local and global conformational stability of hemoglobin by the allosteric effectors BPG and IHP

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Modification of local and global conformational stability of hemoglobin by the allosteric effectors BPG and IHP

Ali, Md. Eaqub (2004) Modification of local and global conformational stability of hemoglobin by the allosteric effectors BPG and IHP. Masters thesis, Concordia University.

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Abstract

FTIR studies of the effects of BPG and IHP binding on the p(SH) stretching vibrations of human deoxyhemoglobin A (deoxyHbA) between 25 and 75{493}C reveal that the effectors stabilize the p(SH) peak of Cysβ93 at 2576 cm -1 at high temperatures (55{493}C or above). In the presence of the effectors, the p(SH) peak of Cys{460}104 at 2558 cm -1 is broadened, and the p(SH) shoulder of Cys{460}112 at 2564 cm -1 fluctuates in intensity with increasing temperature, indicating that the effectors destabilize the {460} 1 β 1 interface of the deoxyHbA tetramer (2{460}2β). At 25{493}C, the Soret CD bands of 0.5 mM effector-bound deoxyHbA are observed at 418 and 432 nm with ellipticities of -2.4 and +28 M -1 cm -1 , respectively. These signals are intensified by 2-5 units at 55{493}C. In contrast, effector-free deoxyHbA loses {598}50% of its Soret CD absorption and {598}10% of its unpolarized Soret absorption on heating to 55{493}C. Effector binding also stabilizes the 287-nm negative CD band and the three-valley CD absorption between 250-270-nm, which reflect changes at the {460} 1 β 1 interface. FTIR-monitored thermal unfolding of 3.0 mM deoxyHbA reveals that loss of the {460}-helical absorption at 1653 cm -1 occurs in three phases. These may be associated with tetramer [arrow right] dimer, dimer [arrow right] monomer and monomer [arrow right] denatured-monomer transitions. In the presence of BPG and IHP, the FTIR denaturation curves are shifted by {598}5{493}C to lower temperature, indicating that effector binding destabilizes the secondary structure of deoxyHbA.

Divisions:Concordia University > Faculty of Arts and Science > Chemistry and Biochemistry
Item Type:Thesis (Masters)
Authors:Ali, Md. Eaqub
Pagination:x, 71 leaves : ill. ; 29 cm.
Institution:Concordia University
Degree Name:M. Sc.
Program:Chemistry and Biochemistry
Date:2004
Thesis Supervisor(s):English, Ann M
ID Code:8127
Deposited By:Concordia University Libraries
Deposited On:18 Aug 2011 14:16
Last Modified:18 Aug 2011 14:16
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