Isoelectric forms of bacteriorhodopsin from Halobacterium halobium.
Isoelectric focusing was performed on bacteiorhodopsin isolated from Halobacterium halobium, R1 strain, solubilized in Nonidet P-40, on sucrose density gradient stabilized columns. When 560 nm absorbance was monitored, four forms of bacteriorhodopsin were observed, having isoelectric points (pI) of: A. 3.93; B, 4.43; C, 5.03; D, 5.49. Instability of some of the isoelectric forms during the very process of electrofocusing was observed. When focused over a period of 6 days, the relative abundance of the forms changed although their pI values remains constant. Refocusing of the isolated forms A or B led to the production f form C. The latter species was stable to refocusing. Form B was unstable to storage either as an aqueous suspension of the purple membrane or as a detergent extract. Each of the forms had the absorption spectrum typical for bacteriorhodopsin and each showed identical patterns after sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
D001436:Bacteriorhodopsins / Q000378:metabolism*; D002338:Carotenoids / Q000378:metabolism*; D003902:Detergents; D004355:Drug Stability; D004591:Electrophoresis, Polyacrylamide Gel; D006217:Halobacterium / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D017830:Octoxynol; D011092:Polyethylene Glycols; D013057:Spectrum Analysis; D013997:Time Factors
D003902:Detergents; D002338:Carotenoids; D011092:Polyethylene Glycols; D001436:Bacteriorhodopsins; D017830:Octoxynol; C010615:Nonidet P-40