Anomalies in the Absorption Spectrum and Bleaching Kinetics of Visual Purple

Abstract

Visual purple from winter frogs shows an intermediate yellow color during bleaching by light; summer extractions do not. This seasonal effect can be duplicated by variations in the hydrogen ion concentration and in the temperature of the solutions. Increasing the pH approximates the summer condition, while decreasing the pH approximates the winter condition. Temperature has no effect on the bleaching of alkaline solutions but greatly influences acid solutions. At low temperatures the bleaching of add solutions resembles the winter condition, while at higher temperatures it resembles the summer condition. A photic decomposition product of frog retinal extractions is an acid-base indicator: it is yellow in acid and colorless in alkaline solution. Its color is not dependent upon light. The hydrogen ion concentration of visual purple solutions does not change under illumination, nor is there a difference in the pH of summer and winter extractions. Bile salt extractions of visual purple are usually slightly acid. The conflicting results of past workers regarding the appearance of "visual yellow" may be due to seasonal variation with its differences in temperature, or to the presence of base in the extractions. It is also possible that vitamin A may be a factor in the seasonal variation. The photic decomposition of visual purple in bile salts solution, extracted from summer frogs, follows the kinetics of a first order reaction. Visual purple from winter frogs does not conform to first order kinetics. Photic decomposition of alkaline, winter visual purple extractions also follows a first order equation. Acid, winter extractions appear to conform to a second order equation, but this is probably an artefact due to interference by the intermediate yellow.

On Rhodopsin in Solution

“…In this way the kinetics of the isolated light reaction might be explored. Chase (1935-36), using irradiation intensities much lower than those of the present research, found the kinetics of bleaching in acid and cold solutions to present "anomalies," while in warmer and more alkaline solutions the results permitted simpler interpretation. Chase ascribed these differences to the appearance of yellow reaction products under the former conditions, their absence under the latter.…”

“…--Chase (1935-36) has studied the bleaching of rhodopsin solutions at various pH's and moderately low intensities of irradiation. In alkaline solution bleaching was found to be rapid and kinetically simple; in acid solution, slow and relatively complex.…”

Mechanisms of aldosterone action in tight epithelia

“…The recently available procedures for studying Na + channels in isolated apical vesicles (Chase & A1-Awqati, 1983;Garty & Asher, 1985), lipid bilayers (Sariban-Sohraby et al, 1984b) and membrane paths (Hamilton & Eaton, 1985), may help to resolve this issue. A more likely possibility would be an aldosterone-induced reaction at the level of the apical membrane, which activates nonconductive, pre-existing, channels or increases the life-time of the channel open state.…”

The Reduction of Retinene1 to Vitamin A1 in Vitro

“…The retinenel-protein which results from bleaching rhodopsin in solution is almost colorless when alkaline and bright yellow when acid (Chase, 1935-36).…”