Laser activation of rapid absorption changes in spinach chloroplasts and chlorella

Abstract

The kinetics of the 520 mmu absorption change in spinach chloroplasts and Chlorella vulgaris following a flash from the ruby laser have been determined as follows: rise halftime </= 0.3 x 10(-6) second; rapid recovery halftime = 5 to 6 x 10(-6) second; intermediate recovery halftime = 4 x 10(-4) second (spinach chloroplasts only); slow recovery halftime = 12 to 170 x 10(-3) second, dependent on the measuring light intensity and aerobicity of the suspension.The rapid phase of the 520 mmu reaction is approximately independent of temperature, from 295 degrees to 77 degrees Absolute.With increasing oxygenation of the sample, the extent of the rapid phase decreases, the extent of the slow phase increases, while the extent of the intermediate phase in spinach chloroplasts remains constant.In spinach chloroplasts, no recovery halftime of the 3 recovery phases for the 520 mmu absorption change was observed to correspond to the halftime for oxidation of cytochrome f (t((1/2)) = 1.3 x 10(-3) second).