Stimulation of photosystem I-induced oxidation of chloroplast cytochrome b-559 by pre-illumination and by low pH.

(1) The proportion of higher plant chloroplast cytochrome b-559 oxidizable during illumination by low intensity 732 nm light increases as the pH is decreased below 6.5. At pH 5.

Changes in E. coli cell envelope structure caused by uncouplers of active transport and colicin E1.

It is of interest to inquire whether agents that uncouple or deenergize membranes cause concomitant structural changes. The agents considered here are the uncoupler carbonyl cyanide-p-trifluoromethoxyphenylhydrazone and the bacteriocidal protein colicin E1, agents for which there is some precedent for believing that they interact with membranes. In intact E.

Light-induced turnover of chloroplast cytochrome b-559 in the presence of N-methylphenazonium methosulphate.

In the presence of 0.1-5 muM N-methylphenazonium methosulphate approx. 50-70% oxidation of cytochrome b-559 can be induced by far-red light.

Response of an Escherichia coli-bound fluorescent probe to colicin E1.

The fluorescent probe, 8-anilino-1-napthalenesulfonate (ANS) binds to Escherichia coli, showing an enhanced fluorescence. The interaction of colicin E1 with sensitive cells causes an increase of about 100% in the fluorescence of the bound ANS, and this change at equilibrium has an apparent "all-or-none" nature as a function of E1 multiplicity. Approximately 6 to 8% of the ANS is bound to the cells at equilibrium.