Studies on the red absorption band of chlorophyll a in vivo.

Abstract

It was studied whether certain earlier observed weak shoulders on the red absorption band of chlorophyll a in vivo might represent anomalies due to overlap of absorption bands. The results are suggested of the fact that no such anomalies occur. It is therefore concluded that the present study supports the concept holding that, at least, 6 rather than 4 chlorophyll a forms may be present in the state in vivo. The true position of the Ca680 absorption maximum is suggested to occur at a wavelength at least 4 mμ longer than that actually measured in spectra of cells and chloroplast suspensions. The data suggest that Ca667 is likely to function in the Hill reaction with p-benzoquinone as an oxidant at least as efficiently as Ca670. The possible significance of the chlorophyll a forms other than Ca670, Ca680, Ca695 and Ca700 is discussed.