TETRACAINE INDUCES THE FORMATION OF THE SPECTRAL FORM OF BACTERIORHODOPSIN BR-470 IN PURPLE MEMBRANES OF HALOBACTERIAстатья
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Дата последнего поиска статьи во внешних источниках: 29 мая 2015 г.
Местоположение издательства:Road Town, United Kingdom
Первая страница:134
Последняя страница:140
Аннотация:The influence of tetracaine (dimethylamino ester of p-butylaminobenzoic acid) on bacteriorhodopsin in purple membranes of Halobacterium halobium was investigated. In the deprotonated form at pH 9.5, tetracaine induces a hypsochronic shift of the absorption band from 570 to 470 nm (the form BR-470). According to the data of resonance Raman spectroscopy, the charge surroundings of the chromophore of the form BR-470 is greatly changed in comparison with the native protein. The form BR-470 possesses photochemical activity; moreover, the kinetics of the formation of the intermediate M (absorption maximum at 380 nm) is close to that for the analogous intermediate in the cycle of intact bacteriorhodopsin, while the time constant of decomposition of M is approximately 10(4) times greater (approximately 60 sec and 8 msec, respectively). According to the data of differential scanning microcalorimetry, tetracaine in the deprotonated form does not affect the position and amplitude of the denaturation peak of bacteriorhodopsin, which is an indication of the absence of any significant changes in the structure of the protein. In the protonated form at pH 7.0, tetracaine has no effect on the kinetic and spectral characteristics of bacteriorhodopsin but increases the temperature of its denaturation by 2-degrees-C. The influence of tetracaine in this case is analogous to the nonspecific influence of univalent cations on purple membranes.