TCB Publications - Abstract

TCB Publications - Abstract

Ilya Logunov, William Humphrey, Klaus Schulten, and Mordechai Sheves. Molecular dynamics study of the 13-cis form (bR548) of bacteriorhodopsin and its photocycle. Biophysical Journal, 68:1270-1282, 1995. (PMC: 1282023)

LOGU95C The structure and the photocycle of bacteriorhodopsin (bR) containing 13-cis, 15-/it syn retinal, so-called $bR_{548}$, has been studied by means of molecular dynamics simulations performed on the complete protein. The simulated structure of $bR_{548}$ was obtained through isomerization of in situ retinal around both its $C_{13}-C_{14} $ and its $C_{15}-N$ bond starting from the simulated structure of $bR_{568}$ described previously, containing all-trans, 15-anti retinal. After a 50-ps equilibration, the resulting structure of $bR_{548}$ was examined by replacing retinal by analogues with modified $\beta$-ionone rings and comparing with respective observations. The photocycle of $bR_{548}$ was simulated by inducing a rapid 13-cis, 15-anti $\rightarrow$ all- trans, 15-syn isomerization through a 1-ps application of a potential that destabilizes the 13-cis isomer. The simulation resulted in structures consistent with the J, K, and L intermediates observed in the photocycle of $bR_{548}$. The results offer an explanation of why an unprotonated retinal Schiff base points to the intracellular rather than to the extracellular site. The simulations suggest also that leakage from the $bR_{548}$ to the $bR_{568}$ cycle arises due to an initial 13-cis, 15-anti ($\rightarrow$) all-trans, 15-anti photoisomerization.

Download Full Text

The manuscripts available on our site are provided for your personal use only and may not be retransmitted or redistributed without written permissions from the paper's publisher and author. You may not upload any of this site's material to any public server, on-line service, network, or bulletin board without prior written permission from the publisher and author. You may not make copies for any commercial purpose. Reproduction or storage of materials retrieved from this web site is subject to the U.S. Copyright Act of 1976, Title 17 U.S.C.

Download full text: PDF ( 1.3MB), PS (568.8KB), Journal