Nitrogenase activity in extracts of heterocystous and non-heterocystous blue-green algae

Summary Cell-free extracts capable of acetylene reduction and cyanide reduction have been prepared from heterocystous (Anabaena cylindrica) and non-heterocystous (Plectonema boryanum 594) blue-green algae. Extracts from Anabaena were obtained from cultures grown in blulk under aerobic conditions, while the Plectonema cultures were grown in bulk on nitrate-nitrogen, then washed free from nitrate and sparged with A/CO₂ for 40 h after which time maximum nitrogenase activity was detected. The nitrogenases of both algae are similar and resemble in many respects nitrogenases from bacteria and legumes. Activity is located primarily in a 40,000xgx15 min supernatant fraction and the rate of C₂H₂ reduction observed is about 10 per cent of whole cell activity. ATP and a source of reducing power (Na₂S₂O₄) are required for efficient functioning of the enzyme. ATP-dependent hydrogen evolution occurs, the extracts are cold labile and highly sensitive to oxygen and the oxygen inhibition is irreversible.     

Die Rolle des Carnitins im Intermedi?rstoffwechsel

Ohne Zusammenfassung Mit 2 Abbildungen Aus dem Hauptlaboratorium des Stadtkrankenhauses, 7033 Leipzig, Friesenstr. 8 (Direktor: Prof. Dr. med. habil.D. Lohmann) Herrn Prof. Dr. Dr. Dr. h.c. Dr. h.c.E. Strack zum 70. Geburtstag in Dankbarkeit.     

Intracardiac Shunt-Use of the Hydrogen-Sensitive Catheter to Clarify False Positive Diagnosis of Left-to-Right Shunt

The charts of 142 patients who had diagnostic right heart catheterization with conventional oximetry, oxygen content determinations and hydrogen electrode curve recording for left-to-right shunt were reviewed. A false positive diagnosis of surgical significance would have been made in nine patients if the hydrogen electrode had not been used. In addition, a diagnosis of left-to-right shunt could have been made at the wrong chamber level in three additional cases.