BIOPHYSICAL STUDIES OF MICROBIAL CELL WALLS. PART 2. ELECTROPHORESIS: APPARATUS AND EXPLORATORY EXPERIMENTS.
NAVAL RESEARCH LAB WASHINGTON D C
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Electrophoresis is one of the few physicochemical methods available for the quantitative study of the nature of microbial cell surfaces. Microelectrophoretic apparatus suitable for work with both intact cells and their isolated cell walls has been constructed. Distinguishing features of the system are palladium-hydrogen electrodes, a precision-built flat observation chamber, phase contrast optics, and a water bath for the rapid dissipation of ohmic heat and maintenance of a defined temperature. The electrophoretic mobilities of selected organisms were reproducible, homogeneous, and insensitive to the presence of substances leached from glass vessels. The surfaces of the microbes chosen for this investigation were dominated by electronegative charges derived most probably from carboxyl and phosphate groups. The adsorption of anions from the suspending media made an insignificant contribution to the charge. Amino groups appeared to be entirely absent. The mobilities of isolated cell walls under varying conditions of pH and ionic strength were very similar to those of the corresponding intact cells. Thus, studies on isolated cell walls can provide a valid way of characterizing the wall surface which is especially useful under conditions where the intact cells are likely to be lysed or are pathogenic. Author