The influence of the 5-methyl group in bacteriorhodopsin

✍ Scribed by M. Groesbeek; E. F. J. de Vries; J. A. Berden; J. Lugtenburg

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 594 KB
• Volume: 112
• Category: Article
• ISSN: 0165-0513
• DOI: 10.1002/recl.19931120505

✦ Synopsis

Abstract

All‐E‐5‐bromo‐5‐demethylretinal was prepared in 6% yield starting from 4,4‐dimethyl‐2‐cyclohexenone via 2‐bromo‐6,6‐dimethyl‐1‐cyclohexenecarboxaldehyde. The crucial step in the preparation of the intermediate is a 2,3 Wittig rearrangement. 5‐Bromo‐5‐demethylbacteriorhodopsin is easily formed from all‐E‐5‐bromo‐5‐demethylretinal and bO. Due to the fact that the bromo substituent has about the same steric requirements as the 5‐methyl group, the influence of electronic factors on the properties of bacteriorhodopsin could be studied. We conclude that the contribution of the 5‐methyl group in bR to the proton‐pump action and opsin shift is due to its electron‐donating properties.