Intersubunit Interactions Associated with Tyr42 Stabilize the Quaternary-T Tetramer but Are Not Major Quaternary Constraints in Deox

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• 作者：Jeffrey S. Kavanaugh ; Paul H. Rogers ; Arthur Arnone ; Hilda L. Hui ; Anita Wierzba ; Alice DeYoung ; Laura D. Kwiatkowski ; Robert W. Noble ; Laura J. Juszczak ; Eric S. Peterson ; and Joel M. Friedman
• 刊名：Biochemistry
• 出版年：2005
• 出版时间：March 15, 2005
• 年：2005
• 卷：44
• 期：10
• 页码：3806 - 3820
• 全文大小：476K
• 年卷期：v.44,no.10(March 15, 2005)
• ISSN：1520-4995

文摘

Previous mutational studies on Tyr42s/gifchars/alpha.gif" BORDER=0> variants as well as the current studies on the mutanthemoglobin s/gifchars/alpha.gif" BORDER=0>Y42A show that the intersubunit interactions associated with Tyr42s/gifchars/alpha.gif" BORDER=0> significantly stabilizethe s/gifchars/alpha.gif" BORDER=0>1s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">2 interface of the quaternary-T deoxyhemoglobin tetramer. However, crystallographic studies,UV and visible resonance Raman spectroscopy, CO combination kinetic measurements, and oxygen bindingmeasurements on s/gifchars/alpha.gif" BORDER=0>Y42A show that the intersubunit interactions formed by Tyr42s/gifchars/alpha.gif" BORDER=0> have only a modestinfluence on the structural properties and ligand affinity of the deoxyhemoglobin tetramer. Therefore, thes/gifchars/alpha.gif" BORDER=0>1s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">2 interface interactions associated with Tyr42s/gifchars/alpha.gif" BORDER=0> do not contribute significantly to the quaternaryconstraints that are responsible for the low oxygen affinity of deoxyhemoglobin. The slight increase inthe ligand affinity of deoxy s/gifchars/alpha.gif" BORDER=0>Y42A correlates with small, mutation-induced structural changes that perturbthe environment of Trp37s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">, a critical region of the quaternary-T s/gifchars/alpha.gif" BORDER=0>1s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">2 interface that has been shown tobe the major source of quaternary constraint in deoxyhemoglobin.