Über das Bakteriochlorophyll der Purpurbakterien. II. Mitteilung. Beiträge zur Physiologie der Farbstoffe der Purpurbakterien.

Abstract

Rhodo-bacillus palustris was grown for 4 weeks on a previously described medium (see B. A. 6: Entry 6537). The green pigment was extracted from the centrifuged mass of cells with 82% acetone and the extract worked up by the Willstatter method for preparing chlorophyll. Each 25 liters of medium yielded about 500 mgm. of pure pigment. Despite marked spectral differences in the native state, the pigment is related to chlorophyll, and, like it, occurs in 2 modifications, a and b. Form b greatly predominates, and has the same elementary composition as chlorophyll b, with 1 methoxyl group and 1 Mg. It contains phytol or a similar constituent. Its Mg-free degradation products are similar to those of chlorophyll b but only the lower ones are identical. The author prefers the name bacteriochlorophyll to the former term bacteriochlorin. Mild oxidizing agents oxygenate bacteriochlorophyll to a compound of the spectral type of chlorophyll, but, in contrast to chlorophyll, it is readily reduced by mild chemical reducing agents or even by the passage of nitrogen through the solution. The pigment is probably common to both the Thiorhodaceae (Chromatioideae) and the Athiorhodaceae (Rhodobacterioideae) and closely related to the bacterioviridin of [Van Tieghem''s] green bacteria. Its high lability is undoubtedly of physi-ological significance and because of its amenability to spectroscopic control can be made the basis of chemical investigations on photosynthesis and the labile groupings present in chlorophyll.