Properties of heterocysts isolated with colloidal silica.
A method is described for the isolation of heterocysts that are virtually free of contaminating cell debris after sonication of aerobically grown Anabaena 7120. Isolated heterocysts reduced acetylene in a light-dependent process in the absence of exogenously provided ATP; heterocysts supplied with ATP and Na2S2O4 reduced acetylene slowly in the dark but still showed a marked light activation. Nitrogenase activity was greatest in fractions containing intact heterocysts. Up to 13% of the activity of the intact filaments was accounted for in the isolated heterocyst preparation. Isolated heterocysts took up O2 in a light-independent process; O2 uptake with added NADP+ was enhanced by pyruvate, isocitrate and intermediates of the oxidative pentose pathway.
D002469:Cell Separation / Q000379:methods; D003102:Colloids; D000458:Cyanobacteria / Q000166:cytology / Q000378:metabolism*; D008027:Light; D009249:NADP / Q000378:metabolism; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000032:analysis; D010101:Oxygen Consumption; D012822:Silicon Dioxide; D013010:Sonication; D014461:Ultracentrifugation / Q000379:methods
D003102:Colloids; D009249:NADP; D012822:Silicon Dioxide; D009591:Nitrogenase