ZfN: Search Results

1	Author	Hans-Dieter Müller, Helmut Görisch	Requires cookie*
	Title	Archaebacterial Citrate Synthases: The Enzymes from the Thermoacidophiles Sulfolobus acidocaldarius and Thermoplasma acidophilum Show pro-S Stereospecificity
	Abstract	Citrate synthase from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius was purified 365-fold to electrophoretic homogeneity. At 40 °C and pH 8.1 the homogeneous enzyme shows a specific activity of 73 units per mg, which corresponds to a turnover number of 44 sec-1. Citrate synthase from S. acidocaldarius shows pro-S stereospecificity, as is found with a partially purified preparation of the enzyme from Thermoplasma acidophilum, another thermoacidophilic archaebacterium.
	Reference	Z. Naturforsch. 44c, 927 (1989); received July 12 1989
	Published	1989
	Keywords	Citrate Synthase, Stereospecificity, Archaebacteria, Sulfolobus acidocaldarius, Thermoplasma acidophilum
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	TEI-XML for	default:Reihe_C/44/ZNC-1989-44c-0927.pdf
	Identifier	ZNC-1989-44c-0927
	Volume	44

2	Author	Michaela Dane, Kerstin Steinert, Kordula Esser, Susanne Bickel-Sandkötter, Francisco Rodriguez-Valera	Requires cookie*
	Title	Properties of the Plasma Membrane ATPases of the Halophilic Archaebacteria Haloferax mediterranei and Haloferax volcanii
	Abstract	Both, Haloferax mediterranei and Haloferax volcanii membranes contain ATPases which are capable of hydrolyzing ATP in presence of Mg2+ or M n2+. The ATPases require high con centrations of NaCl, a pH value of 9, and high temperatures up to 60 °C. Free manganese ions inhibited the enzyme activity of either ATPase. The ATPases of H f. mediterranei and H f. vol canii, respectively, show different sensitivities to inhibitors of ATP hydrolysis. ATP hydrolysis of isolated H f. mediterranei ATPase was inhibited by N aN 3, which was reported to be specific for F-ATPases, by nitrate and N-ethylmaleimide (NEM), which are specific inhibitors of V-ATPases. ATP hydrolysis of H aloferax mediterranei membranes was not inhibited by DCCD , but [14C]DCCD was bound to a 14 kDa peptide of the isolated, partially purified en zyme. Furthermore, the ATPase was inactivated by preincubation with 7-chloro-4-nitro-benzofurazan (NBD-C1). The ATPase activity of H f. volcanii membranes was inhibited by NEM but not by nitrate and N aN 3. SDS gel electrophoresis of the partially purified enzyme of Haloferax mediterranei showed putative ATPase subunits of 53. and 7.5 kDa. Immunoblots showed cross reactivity between a 53 kDa peptide and anti-$ (chloro plast F(), as well as between 53, 50 and 47 kDa peptides and an ATPase antibody of Methano-sarcina barkeri. The results will be discussed in context with the placement of the archaebac-terial ATPases (A-ATPases) between F-and V-ATPases.
	Reference	Z. Naturforsch. 47c, 835—844 (1992); received June 29/September 10 1992
	Published	1992
	Keywords	Archaebacteria, Plasma Membrane, ATPase, Subunits, ATP Hydrolysis, Inhibition
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	TEI-XML for	default:Reihe_C/47/ZNC-1992-47c-0835.pdf
	Identifier	ZNC-1992-47c-0835
	Volume	47