LOCALIZATION OF RESPIRATORY ENZYMES IN INTRACYTOPLASMIC MEMBRANES OF AZOTOBACTER AGILIS

Abstract

Thin sections of the cells of Azotobacter agilis which have been disrupted by sonic treatment, by osmotic shock or by ballistic disintegration reveal a network of internal membranes in the form of vesicles and tubules. The internal membranes are attached to the envelope. Treatment in a Mickle disintegrator of envelopes emptied of cytoplasm by osmotic shock results in the loss of the internal membranes and a concomitant release of reduced diphos-phopyridine nucleotide oxidase from the envelopes. Thus, the intracytoplasmic membranes are the probable locus of the respiratory enzymes of the cell. Thin sections of whole cells show tubular intracytoplasmic membranes which are obscured by ribosomes and other dense cytoplasmic constituents.