On the regulatory properties of a halophilic malic enzyme fromHalobacterium cutirubrum

Summary The NADP-linked malic enzyme fromHalobacterium cutirubrum is strongly inhibited by acetyl-CoA and NADH, and rather weakly inhibited by oxaloacetate and glyoxylate, in the presence of very high KCl concentrations (3,M), considered physiological for the extremely halophilic bacteria.This work was supported by grants from the consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, and the Consejo de Investigaciones de la Universidad Nacional de Rosario. JJC and MCV are members of the Carrera del Investigador Científico of the former and the latter institutions, respectively.     

On the role of divalent cations in the reaction mechanism of malic enzyme.

The kinetic order of addition of Mg2+ and L-malate to malic enzyme has been determined. Mg2+ is the first to bind, and probably acts as a link between the substrate and the active site.     

The halophilic properties of pyruvate kinase from Vibrio costicola, a moderate halophile.

Pyruvate kinase from Vibrio costicola, a moderate halophile, appears to be adapted to functioning in the presence of salt. Its stability depends on the ionic strength of the medium. The amino acid composition resembles that of other halophilic enzymes. It is proposed that the halophilic pyruvate kinase utilizes preferentially the Mn++ cofactor which forms more stable complexes in the presence of physiological concentrations of salt.     

Sex linkage of malic enzyme inXenopus laevis

Genetic analysis of mME variants (mitochondrial malic enzyme, E.C. 1.1.1.40) inXenopus laevis revealed sex linkage of the mMe locus and indicated a WZ/ZZ type of sex determination. Codominant mMe alleles occur on both W and Z chromosomes, with a recombination frequency of 6.1%±1.5% between mMe and the sex-determining locus (or region).     

Sex linkage of malic enzyme in Xenopus laevis

Genetic analysis of mME variants (mitochondrial malic enzyme, E.C. 1.1.1.40) in Xenopus laevis revealed sex linkage of the mMe locus and indicated a WZ/ZZ type of sex determination. Codominant mMe alleles occur on both W and Z chromosomes, with a recombination frequency of 6.1% +/- 1.5% between mMe and the sex-determining locus (or region).     

The halophilic properties of pyruvate kinase fromVibrio costicola,a moderate halophile

Summary Pyruvate kinase fromVibrio costicola, a moderate halophile, appears to be adapted to functioning in the presence of salt. Its stability depends on the ionic strength of the medium. The amino acid composition resembles that of other halophilic enzymes. It is proposed that the halophilic pyruvate kinase utilizes preferentially the Mn⁺⁺ cofactor which forms more stable complexes in the presence of physiological concentration of salt.     

Partial sequence of the gene for a serine protease from a halophilic archaeumhaloferax mediterranei R4, and nucleotide sequences of 16S rRNA encoding genes from several halophilic archaea

A part of the gene coding for a halophilic serine protease from a halophilic archaeumHaloferax mediterranei R4 was amplified by PCR and its 672 nucleotide sequence was determined. Tentative translation to the amino acid sequence suggested that the enzyme was quite similar to halolysin produced by another halophilic archaeum strain 172P1. Nucleotide sequences of 16S rRNA encoding genes from 9 halophilic archaea were determined. Alignment of 19 sequences known so far showed that there are more than 20 positions carrying bases or deletions specific for each halobacterial genus:Halobacterium, Haloarcula, Haloferax, andHalococcus.     

On the electrophoretic properties of a purified enterogastrone preparation

Zusammenfassung 1. Es wird ein Extrakt von Schweinedarm (Enterogastron), der die durch Histamin erzeugte Magensekretion herabsetzt, elektrophoretisch untersucht.2. Die aktive Enterogastronfraktion scheint keine elektrophoretische Beweglichkeit zu besitzen.3. Enterogastron ist wahrscheinlich keine proteinähnliche Substanz.4. Die Resultate werden besprochen und zu früheren Untersuchungen über die Chemie des Enterogastrons in Beziehung gesetzt.     

On the mineralocorticoid and hypertensogenic properties of 16beta-hydroxy-dehydroepiandrosterone.

Dosages of either 1 or 2 mg daily of 16beta-hydroxy-dehydroepiandrosterone, given to mononephrectomized, salt-loaded female rats, had no detectable effect upon saline consumption, blood pressure, kallikrein excretion or heart and kidney weight. Its alleged mineralocorticoid properties, as judged by these criteria, were not demonstrable.     

Is ATP synthesized by a vacuolar-ATPase in the extremely halophilic bacteria?

The proton-dependent synthesis of ATP was demonstrated in representative members of the generaHalobacterium, Haloarcula, andHaloferax. In all cases, synthesis was not inhibited by nitrate or N-ethylmaleimide, inhibitors of the vacuolar-like ATPase found in Archaea, but was affected by azide, an inhibitor of F₀F₁-ATP syntheses. These observations extend the earlier observations withHalobacterium saccharovorum and suggest that ATP synthesis in these organisms is brought about by an F₀F₁-APT synthase.     

Partial purification of a plasma-kinin-forming enzyme from horse urine

Zusammenfassung Durch Chromatographie mit Diäthylamino-äthyl-cellulose nach Ammoniumsulfat-Fraktionierung wurde ein Plasma-Kinin-freisetzendes Ferment aus Pferdeharn teilweise (80×) gereinigt. Das so gereinigte Präparat war gegen Pferde-, Menschen-, Rinder (Fraktion IV-4)- und Ratten-Blutplasma, nicht aber gegen Schweine-(Fraktion IV-4)-Globuline wirksam. Durch Sojabohnen-Trypsininhibitor oder Ovomucoid erfolgt keine Hemmung. Präparate von verschiedenem Reinheitsgrad zeigten entsprechendep-Toluenesulfonyl-l-arginin-methylester-spaltende und Kinin-freisetzende Wirksamkeit.

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Read before the XIIth Annual Meeting of the Sociedade Brasileira para o Progresso da Ciência, Piracicaba, July 1960; supported by Grant No. 58217 from the Rockefeller Foundation.     

The physical state of alkali ions in a Halobacterium: Some NMR results

Summary Nuclear magnetic relaxation measurements of the ions Na⁺, Rb⁺ and Cs⁺ in a Halobacterium sp. are described. The results support a theoretical model which involves the binding of intracellular alkali ions.We wish to thank the European Molecular Biology Organization (EMBO) and the Nederlandse Stichting voor Zuiver Wetenschappelijk Onderzoek (ZWO) for the financial support that made our stay in Groningen possible.