Amnon Albeck

Bar Ilan University | BIU · Department of Chemistry

The picosecond molecular dynamics in an artificial bacteriorhodopsin (BR) pigment containing a structurally modified all-trans retinal chromphore with a six-membered ring bridging the C11=C12-C13 positions (BR6.11) are measured by picosecond transient absorption and picosecond time-resolved fluorescence spectroscopy. Time-dependent intensity and sp...

Absorption maxima and C-13 NMR chemical shifts were measured for retinal iminium salts. A good correlation was found between the absorption maxima and the C-13 chemical shifts of the retinal polyene carbons within the same solvent system. The chemical shifts of the odd-membered carbons of the polyene are affected much more than the even carbons by...

The absorption maximum (568 nm) of light-adapted bacteriorhodopsin bR568 undergoes reversible changes after acidification. At pH 2.9, the absorption shifts to 605 nm (forming bR605) and it blue shifts to 565 nm, after further acidification to pH approximately 0.5 (forming bR565). Molecular models accounting for such acid-induced changes are relevan...

The photolysis intermediates of an artificial bovine rhodopsin pigment, cis-5,6-dihydro-isorhodopsin (cis-5,6,-diH-ISORHO, lambda max 461 nm), which contains a cis-5,6-dihydro-9-cis-retinal chromophore, are investigated by room temperature, nanosecond laser photolysis, and low temperature irradiation studies. The observations are discussed both in...

The artificial 11-cis-retinal (I) (synthesis already published) forms a pigment when incubated with bovine opsin.

The phosphonium salt (I) of β-ionone undergoes Wittig reaction with the aldehydes (II) to give the trans- and cis-tetraenones (III) and (IV).

Artificial bacteriorhodopsin (bR) pigments based on synthetic retinal analogues with selectively blocked single and double bonds were prepared. It was shown that rotations around single bonds C12-C13 and C10-C11 and isomerizations of C11=C12 and C9=C10 are not required either for initiating the photocycle of all-trans-bR. or for forming its M412 in...

Artificial bacteriorhodopsin pigments based on synthetic retinal analogues carrying an electron-withdrawing CF3 substituent group were prepared. The effects of CF3 on the spectra, photocycles, and Schiff base pKa values of the pigments were analyzed. A reduction of 5 units in the pKa of the Schiff base is observed when the CF3 substituent is locate...

Artificial bacteriorhodopsin (bR) pigments based on synthetic retinal analogues with selectively blocked single and double bonds are prepared and submitted to pulsed laser photolysis. Similar experiments are carried out with short-chain aromatic analogues. It is concluded that only the C13=C14 double bond can be isomerized in the primary photoproce...