The amount of phospholipids in the chromatophores and the B800-850 and
B890 pigment-protein complexes from the sulfur bacterium Chromatium m
inutissimum was measured, and variations in the structure of photosynt
hetic membranes induced by the hydrolysis of phospholipids under the a
ction of phospholipase A(2) were studied. A new spectral form B820, re
lated to the degradation of phospholipids, was revealed. The role of l
ipids in the pigmented structures B800, B850, and B890 is discussed.