INTERACTION OF THE PROTONATED SCHIFF-BASE WITH THE PEPTIDE BACKBONE OF VALINE-49 AND THE INTERVENING WATER MOLECULE IN THE N PHOTOINTERMEDIATE OF BACTERIORHODOPSIN

Citation
Y. Yamazaki et al., INTERACTION OF THE PROTONATED SCHIFF-BASE WITH THE PEPTIDE BACKBONE OF VALINE-49 AND THE INTERVENING WATER MOLECULE IN THE N PHOTOINTERMEDIATE OF BACTERIORHODOPSIN, Biochemistry, 37(6), 1998, pp. 1559-1564
Citations number
50
Categorie Soggetti
Biology
Journal title
ISSN journal
00062960
Volume
37
Issue
6
Year of publication
1998
Pages
1559 - 1564
Database
ISI
SICI code
0006-2960(1998)37:6<1559:IOTPSW>2.0.ZU;2-R
Abstract
The effects of replacing Val49, Thr46, Asp96, and Phe219 in the cytopl asmic domain of bacteriorhodopsin on water O-H stretching vibrational bands and the amide I and imide II bands of the peptide backbone were examined in the M, N, and M-N intermediates. This study is an extensio n of previous work on the L photointermediate [Yamazaki, Y., Tuzi, S., Saito, H., Kandori, H., Needleman, R., Lanyi, J. K., and Maeda, A. (1 996) Biochemistry 35, 4063-4068]. The O-H stretching bands at 3671 cm( -1) in the M intermediate and at 3654 cm(-1) in the N intermediate are shown to originate from the same water molecule. It is located in the region surrounded by the Schiff base, Val49, Thr46, and Phe219 in the M intermediate, and moves closer to Val49 in the M to N reaction. The peptide C-N bond between Val49 and Pro50 and the C=O bond of Val49 un dergo perturbations upon formation of the N intermediate but not the M and N-like M-N states in which the Schiff base is unprotonated. The c arbonyl oxygen of Val49 is proposed to be the acceptor in H-bonding wi th the protonated Schiff base in the N intermediate. The results sugge st that water molecules may be involved in this interaction in the cyt oplasmic region, and may play a role in the accessibility change of th e Schiff base in the L to M to N photocycle steps.