Oxygen evolution and the permeability of the outer envelope of isolated whole chloroplasts.

A rapid oxygraph method of studying the permeability of the envelope of isolated chloroplasts was used. The outer envelope of aqueously isolated whole spinach (Spinacia oleracea L.) chloroplasts in buffer is readily permeable to 3-phosphoglyceric acid, which induces an immediate light dependent oxygen evolution. This light dependent oxygen evolution was completely eliminated by swelling these plastids in an osmotically dilute solution. Exogenous adenosine diphosphate, but not inorganic phosphate, strongly stimulated this oxygen evolution. This indicated that the chloroplast envelope is relatively permeable to adenosine diphosphate.Oxygen evolution and swelling studies indicated that the chloroplast envelope is relatively impermeable to NADP and to ferredoxin.A method is described whereby the percent of whole chloroplasts present in a chloroplast preparation may be rapidly estimated.