Electrophoresis and Isoelectric Focusing of Whole Cell and Membrane Proteins from the Extremely Halophilic Archaebacteria

摘要

The isoelectric points of most proteins from the extremely halophilic archaebacteria are between 4.0 and 4.65 which agrees with the generally high content of glutamic and aspartic acid in proteins from halobacteria. The subunits from two purified halobacterial membrane enzymes (ATPase and nitrate reductase) behaved differently, with respect to isoelectric focusing, silver staining and interaction with ampholytes. Differential behavior was also observed in whole cell proteins from Halobacterium saccharovorum regarding resolution in two-dimensional gels and silver staining. We propose that these differences reflect the existence of two classes of halobacterial proteins, one resembling non-halophilic proteins, and the other possessing unique properties that may be related to salt dependence.