Interaction of the Protonated Schiff Base with the Peptide Backbone of Valine 49 and the Intervening Water Molecule in the N Photointermediate of Bacteriorhodopsin

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• 作者：Yoichi Yamazaki ; Hideki Kandori ; Richard Needleman ; Janos K. Lanyi ; and Akio Maeda
• 刊名：Biochemistry
• 出版年：1998
• 出版时间：February 10, 1998
• 年：1998
• 卷：37
• 期：6
• 页码：1559 - 1564
• 全文大小：87K
• 年卷期：v.37,no.6(February 10, 1998)
• ISSN：1520-4995

文摘

The effects of replacing Val49, Thr46, Asp96, andPhe219 in the cytoplasmic domain ofbacteriorhodopsin on water O-H stretching vibrational bands and theamide I and imide II bands of thepeptide backbone were examined in the M, N, and M_Nintermediates. This study is an extension ofprevious work on the L photointermediate [Yamazaki, Y., Tuzi, S.,Saitô, H., Kandori, H., Needleman,R., Lanyi, J. K., and Maeda, A. (1996) Biochemistry35, 4063-4068]. The O-H stretching bandsat3671 cm^-1 in the M intermediate and at 3654cm^-1 in the N intermediate are shown tooriginate from thesame water molecule. It is located in the region surrounded by theSchiff base, Val49, Thr46, and Phe219in the M intermediate, and moves closer to Val49 in the M to Nreaction. The peptide C-N bond betweenVal49 and Pro50 and the C=O bond of Val49 undergo perturbations uponformation of the N intermediatebut not the M and N-like M_N states in which the Schiff baseis unprotonated. The carbonyl oxygen ofVal49 is proposed to be the acceptor in H-bonding with the protonatedSchiff base in the N intermediate.The results suggest that water molecules may be involved in thisinteraction in the cytoplasmic region,and may play a role in the accessibility change of the Schiff base inthe L to M to N photocycle steps.