Comparative studies on the polypeptide composition of chloroplast lamellae and lamellar fractions

The polypeptide composition of spinach chloroplast membranes and membrane fractions has been examined by the technique of sodium dodecylsulfate-polyacrylamide gel electrophoresis. Chloroplasts were fragmented into grana (Photosystem II enriched) and stroma lamellae (Photosystem I in character) by the French press technique. The grana lamellae were futher fractionated by the use of digitonin into two fractions, one enriched in Photosystem II and the other enriched in Photosystem I. These membranes are composed of at least 15 polypeptides two of which, with approximate weights of 39 and 50 kdaltons, are observed only in granal fractions. Quantitatively the primarily Photosystem II fractions are enriched in polypeptides in the 30-23 kdalton range whereas the Photosystem I (or Photosystem I-enriched) fractions are enriched in polypeptides in the 60-54 kdalton region. The experiments reported show that contamination by soluble proteins or other membranes is negligible. The results indicate that subtle differences in composition account for the large differences in structure and function within the chloroplast membrane system.     

Interaction of polymorphonuclear leukocytes, bradykinin and carragenin. Transference reaction in the rat

1. Injected in the paw of the rat, polymorphonuclear leucocytes do not increase the oedematogen action of bradykinin, but increase the action of lambda carrageenan. 2. This potentiation of carrageenan action is not modified when PG biosynthesis in leucocytes is inhibited by indomethacin or aspirin. It does not appear in rats previously treated by indomethacin or aspirin. 3. Our results suggest that rat polymorphonuclear leucocytes increase the inflammatory reaction, when they are stimulated by carrageenan, by the release of a phospholipase A2 activity which induces PG biosynthesis in rat paw tissues.