Open AccessThe action of lanthanum ions and formaldehyde on the proton‐pumping function of bacteriorhodopsin
Author(s) -
DRACHEV Alexander L.,
DRACHEV Lel A.,
KAULEN Andrey D.,
KHITRINA Lyubov V.
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb07922.x
Subject(s) - bacteriorhodopsin , lanthanum , chemistry , microsecond , formaldehyde , proton , membrane , photochemistry , ion , inorganic chemistry , organic chemistry , biochemistry , quantum mechanics , astronomy , physics
The photochemical cycle and the proton‐pumping function of bacteriorhodopsin modified with lanthanum and formaldehyde has been studied. In both preparations, the M412 → BR 570 transition time has been found to increase considerably. The deceleration of the photochemical cycle has been shown to be accompanied by inhibition of the millisecond phase of the photoelectrical response of bacteriorhodopsin membranes associated with phospholipid‐impregnated collodion film. Photoelectrogenic activity measured with permeable ion probe in proteoliposomes was also inhibited. Effects of lanthanum were reversed by EDTA. Formation of M412 was slightly accelerated and the microsecond electrogenic phase was not affected by lanthanum and by formaldehyde. It is concluded that lanthanum, but not formaldehyde, can be used as a specific reversible inhibitor of the second half of the bacteriorhodopsin photocycle and of the associated H + uptake on the cytoplasmic side of the halobacterial membrane. Possible mechanisms of these effects are discussed.