Multiple forms of cytochrome b in Mycobacterium phlei: kinetics of reduction.

The kinetics of reduction of the b-type cytochromes in the electron transport particles (ETP) from Mycobacterium phlei were studied with nicotinamide adenine dinucleotide, reduced form (NADH) or succinate as electron donors. There appeared to be three active cytochromes b in the ETP,bS563 and bS559, which were reducible by either substrate, and bN563, which was reducible by NADH but not by succinate. In the presence of adenosine 5'-triphosphate, a substantial increase in b563 reduction was observed with succinate at anaerobiosis. This was followed by a decrease in absorption. Adenosine 5'-triphosphate did not effect an increase in cytochrome b563 reduction at transition with NADH, but the occurrence of a secondary decrease in absorption was reflected in a decrease in total enzymatic reduction. The adenosine 5'-triphosphate effect was altered in trypsin-treated ETP, and abolished by uncoupling agents or by removal of the coupling factor-latent adenosine triphosphatase. In the presence of a supernatant fraction obtained during the preparation of the ETP, b563 reduction with succinate was greatly increased. A smaller increase was observed with NADH. Cytochrome b reduction was also studied in ETP inhibited by 2-n-nonylhydroxyquinoline-N-oxide, which appears to inhibit at bS563. On the basis of these data the interrelationships among the b-type cytochromes can be described in relation to the M. phlei electron transport chain.     

Elektronenmikroskopische Untersuchungen an Mycobacterium phlei

Summary The structure and formation of polyphosphate-granules has been investigated by means of ultrathin sections through Mycobacterium phlei.After removing the polyphosphate, a fine grained and scarcely electron-scattering structure was to be seen which, however, was not bordered by a membrane.The granules probably originate in distinct regions of the cytoplasm from irregularly shaped intermediate stages or from agglomerations of micro-granules.Mitochondria-like structures of Mycobacterium phlei are described. Polyphosphates probably may be accumulated in these structures as well.     

Multiple light-induced reactions of cytochromes b and c in Rhodopseudomonas spheroides

Illumination of chromatophore preparations from Rhodopseudomonas spheroides causes the oxidation of a cytochrome c and a slight oxidation of a cytochrome b with a maximum at 560nm. When illuminated in the presence of antimycin A the oxidation of cytochrome c was more pronounced and cytochrome b(560) was reduced; the dark oxidation of cytochrome b(560) was biphasic in the presence of succinate, but not in the presence of NADH, a less effective reductant. Split-beam spectroscopy showed that, in addition to the reduction of cytochrome b(560), another pigment with maxima at 565 and 537nm. was reduced and was more rapidly oxidized in the dark than cytochrome b(560). This pigment, tentatively identified as cytochrome b(565), was also detected in spectra at 77 degrees k, after brief illumination at room temperature; the maxima at 77 degrees k were at 562 and 536nm. In the absence of antimycin A, light caused a transient reduction of cytochrome b(565) and an oxidation of cytochrome b(560). Dark oxidation of b(565) was rapid, even in the presence of antimycin A and succinate. Difference spectra, at 77 degrees k, of ascorbate-reduced minus succinate-reduced chromatophores or of anaerobic succinate-reduced minus aerobic succinate-reduced chromatophores suggested that two cytochromes c were present, with maxima at 547 and 549nm. When chromatophores frozen at 77 degrees k were illuminated both these cytochromes c were oxidized, indicating a close association with the photochemical reaction centre. A scheme involving two reaction centres is proposed to explain these results.     

Myxoxanthophyll als Hauptcarotinoid von Mycobacterium phlei

Zusammenfassung In einem carotinoidreichen Stamm von Mycobacterium phlei wurde neben den Carotinoiden Phytoen, Phytofluen, -Carotin, Neurosporin, Lycopin, - und -Carotin ein Oxycarotinoid aufgefunden, das mit dem Blaualgenpigment Myxoxanthophyll (=Aphanizophyll) identisch zu sein scheint. Der Gehalt an Carotinoiden beträgt 1% des Trockengewichtes der Bakterien; davon liegen 95% in Form des Oxycarotinoids vor. Myxoxanthophyll wurde aus Tetrahydrofuran-Petroläther mehrmals umkristallisiert und charakterisiert.Herrn Professor Dr. Dr. h. c. A. Rippel zum 70. Geburtstag.