PLASTOGLOBULI OF SPINACH - THEIR SIZE, ISOLATION, AND LIPOQUINONE COMPOSITION

The size and frequency of the osmiophilic plastoglobuli of spinach chloroplasts increase with increasing age of chloroplasts. The plastoglobuli of whole or broken chloroplasts, of sediments and in the isolated form show the same size distribution as in situ. There is no evidence that plastoglobuli may arise from thylakoid lipids by ultrasonic treatment of whole chloroplasts. During the centrifugation of broken chloroplasts only a small portion of the plastoglobuli is releazed, the greater portion remains in the sediment together with the chloroplast fragments. The plastoglobuli of spinach-like those of other plants-mainly contain the excess plastidquinones of the benzoquinone type (plastoquinone 45, plastoquinol, α-tocopherol, α-tocoquinone), little vitamin K1 (a naphthoquinone), traces of carotenoids, but no chlorophylls. The lipoquinone content of spinach chloroplasts increases parallel to the augmentation of the size and frequency of the plastoglobuli. © 1969 Springer-Verlag.