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Halorhodopsin; C1- transport; Black lipid membrane; Blue light effect; Photochromism; (Halobacterium)
Abstract:
Halorhodopsin-containing membrane fragments or purified halorhodopsin-containing asolectin vesicles were adsorbed to one side of a black lipid membrane, and the Cl- transport activity was measured under different light conditions. Pump activity of halorhodopsin (HR578) induced by green light decreased in time due to the formation of the inactive species HR410L and sodium azide accelerated this inactivation. Additional illumination of the system with blue light restored full activity. The regulatory function of blue light could also be demonstrated in suspensions of cell envelope vesicles and whole cells by the use of passive proton flow as a measure of the chloride transport activity. The antagonistic action of yellow and blue light suggests that halorhodopsin acts as a photochromic pigment in the intact cell