An improved microelectrophoresis apparatus and technique for studying biological cell surfaces

1. The electrophoretic mobility values for mitochondria prepared from rat kidney and liver measured in 0.125m-potassium chloride-0.02m-tris, pH7.4, are: -0.78(s.e.m.+/-0.02)mu/sec./v/cm. (29 experiments) and -1.06(s.e.m.+/-0.01) mu/sec./v/cm. (21 experiments) respectively. 2. These mobility values are unaffected by washing and spontaneous swelling at 25 degrees , indicating a stable electrokinetic surface. 3. The mobility of rat-kidney mitochondria is unaffected by thyroxine-induced swelling, or by the state of hydration of the rat. 4. pH-mobility curves show similar surface ionogenic groups for kidney and liver mitochondria; their isoelectric points are pH3.9 and pH4.4 respectively.

mentioning

confidence: 99%

The electrophoretic behaviour of mitochondria from kidney and liver of rats

Plummer¹

1965

“…Study of variation in the mobility of bacterial cells with the pH of the suspension medium at constant ionic strength provides information on the nature, and often also on the relative amounts, of different components at the cell surface. Thus surfaces containing only carboxyl groups (Gittens & James, 1960) and those containing both carboxyl and amino groups (Hill et al 1963b) can be recognized by their characteristic pH-mobility curves, by the titration of the appropriate ionogenic group.…”

Section: Resultsmentioning

confidence: 99%

“…Buffer solutions were prepared from sodium barbiturate, sodium acetate and HCI (Michaelis, 1931) with the addition of NaCl to constant I0-02. The electrophoretic mobility was measured by the method of Gittens & James (1960). The technique and precautions described by these authors were rigorously followed.…”

Section: Methodsmentioning

confidence: 99%

Non-protein components of the cell surface of Staphylococcus aureus

James¹,

Brewer²

1968

1. pH-mobility curves of various laboratory strains of Staphylococcus aureus are non-sigmoid in shape, and all pass through a maximum value in the range pH4-5. 2. The maxima in the curves are not due to incomplete washing of the cells, adsorption of buffer components or irreversible surface damage. 3. Mild oxidation of the cell-surface teichoic acid with sodium metaperiodate gives cells that have typical sigmoid pH-mobility curves, characteristic of either a simple carboxyl surface or a mixed carboxyl-amino surface. 4. The results are discussed in terms of a pH-dependent change in the configuration of the teichoic acid molecules at the surface.

“…The apparatus was calibrated by using washed human erythrocytes (Heard & Seaman, 1960). The procedure described by Gittens & James (1960) was followed, particular attention being given to the precautions described by these authors. Mobilities of whole cells were measured at 25°C over the pH range 2.5-8.0 by using buffer solutions prepared from sodium barbiturate, sodium acetate and HCI (Michaelis, 1931), with the addition of NaCl to constant ionic strength (I, 0.02).…”

Section: Dilution Ratementioning

confidence: 99%

Binding of magnesium ions to cell walls of Bacillus subtilis W23 containing teichoic acid or teichuronic acid

Heckels¹,

Lambert²,

Baddiley³

1977

When grown in a chemostat under various nutritional conditions, cells of Bacillus subtilis W23 produce walls containing teichoic acid or teichuronic acid. The binding of Mg2+ to these walls and to the isolated anionic polymers in solution was measured by equilibrium dialysis. In solution the ribitol teichoic acid bound Mg2+ in the molar ratio Mg2+/P=1:1 with an apparent association constant (Kassoc.) of 0.61 X 10(3)M-1, and the teichuronic acid bound Mg2+ in the ratio Mg2+/CO2-=1.1, Kassoc.=0.3 X 10(3)M-1. Cell walls containing teichuronic acid exhibited closely similar binding properties to those containing teichoic acid; in both cases Mg2+ was bound in the ratio Mg/P or Mg/CO2- of 0.5:1 and with a greater affinity than displayed by the isolated polymers in solution. It was concluded that Mg2+ ions are bound bivalently between anionic centres in the walls and that the incorporation of teichoic acid or teichuronic acid into the walls gives rise to similar ion-binding and charged properties. The results are discussed in relation to the possible functions of anionic polymers in cell walls.