) ~ EJB 92 1022 N-Formylmethanofuran(CH0-MFR): tetrahydromethanopterin(H4MPT) formyltransferase (formyltransferase) from the extremely thcrmophilic Methanopyrus kandleri was purified over 100-fold to apparent homogeneity with a 54% yield. The monomeric enzyme had an apparent molecular mass of 35 kDa. The N-terminal amino acid sequence of the polypeptide was determined.The formyltransferase was found to be absolutely dependent on the presence of phosphate or sulfate salts for activity. The ability of salts to activate the enzyme decreased in the order K2HP04 > (NH4)2S04 > K2S04 > Na2S04 > Na2HP04. The salts KCI, NaCl and NH4C1 did not activate the enzyme. The dependence of activity on salt concentration showed a sigmoidal curve. For halfmaximal activity, 1 M K2HP04 and 1.2 M (NH4)2S04 were required. A detailed kinetic analysis revealed that phosphates and sulfates both affected the V,,, rather than the K, for CHO-MFR and H4MPT. At the optimal salt concentration and at 6 5 T , the V,,, was 2700 U/mg (1 U = 1 pmol/ min), the K,,, for CHO-MFR was 50 pM and the K, for H4MPT was 100 pM. At 90"C, the temperature optimum of the enzyme, the V,,, was about 2.5-fold higher than at 65 "C.Thermostability as well as activity of formyltransferase was dramatically increased in the presence of salts, 1.5 M being required for optimal stabilization. The efficiency of salts in protecting formyltransrerase from heat inactivation at 90°C decreased in the order K2HP04 = (NH4)2S04 % KC1 = NH4Cl = NaCl % Na,S04 > Na2HP04. The catalytic mechanism of formyltransferase was determined to be of the ternary-complex type. The properties of the enzyme from M. kandleri are compared with those of formyltransferase from Methanobacterium thermoautotrophicunz, Methanosarcina barkeri and Archaeoglohus fulgidus.Metfzanopyrus kandleri is a novel abyssal hyperthermophilic Archaeon, which grows optimally at 98°C on H2 and C 0 2 with the formation of CH4 (Huber et al., 1989;Kurr et al., 1991). The organism, which belongs to the kingdom of Euryarchaeota (Woese et al., 1990), is the most thermophilic mcthanogen known so far and is phylogenetically unrelated to all other methanogens (Burggraf et al., 1991). The pathway of C 0 2 reduction to CH4 has been shown to be identical to that used in all other methanogens (Rospert et al., 1991).M . kundleri grows on a completely mineral salts medium. The concentrations of salts add up to 250 mM (mostly NaCl; Kurr et al., 1991). Despite these relatively low extracellular concentrations, the intracellular concentration of salts in the organism are very high. The predominant solutes found are 2,3-diphosphoglycerate and potassium ions at concentrations above 3 M (Huber et al., 1989>. The high intracellular salt concentrations in M . kundleri are reflected in the properties of two enzymes involved in methanogenesis: N5,N10-mcthenyltetrahydromethanopterin cyclohydrolase (Breitung et a]., 1991) and N5,N1'-methylenetetrahydromethanopterin reductase (Ma et al., 1991a). The catalytic efficiency (kJK,,,) of both enzymes is incre...

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Tailored hierarchically structured (organo) silica beads with particle diameters between 0.3 and 2.5 mm have been prepared using an emulsion based solÀgel approach. Poly(propylene oxide)-poly(ethylene oxide) triblock copolymers as surfactants, aniline or 1-butanol as solvent and different silanes such as tetraethyl silicate, [3-(2aminoethylamino)propyl]trimethoxysilane and phenyltrimethoxysilane are used to direct morphology and porosity. The silica spheres provide specific surface areas up to 900 m 2 /g and adjustable porosity in the meso-and macroporous region. The texture includes particulate structures with controllable size between 80 nm and 2.5 μm of the silica particles on the inside of the spheres and a macroporous foam-like shell with macropores in the range between 0.2 and 4.0 μm and a thickness of the shell between 0.6 and 44 μm. The high variability of this preparation method and the simultaneous control of the nano-to millimeter scale structure including the porosity as well as the morphology allows one to design tailor-made adsorbents and catalysts.

Cobalt(II)chlorid fu È hrt zum Cobaltkomplex (2 a), in dem zwei Moleku È le des Liganden durch die Pyridinstickstoffatome an das tetraedrisch koordinierte Cobaltatom gebunden sind. Der tetrafunktionalisierte Ligand gem-N 3 P 3 (OC 6 H 5 ) 2 (NHCH 2 CH 2 C 5 H 4 N-2) 4 (8) reagiert mit Cobalt(II)chlorid zu einem zweikernigen Cobalt±Cobaltat Komplex (8 a). Die CoCl-Einheit ist hier durch Wechselwirkungen eines Phosphazenstickstoffatoms und zweier Pyridingruppen cis-vicinal angeordneter Substituenten gebunden, wa È hrend die CoCl 3 -Gruppe mit einer weiteren Pyridineinheit verknu È pft ist. Synthesis, Complex Formation and Crystal Structures of Cyclotriphosphazenes with Pyridylalkylamino GroupsAbstract. A variety of cyclotriphosphazenes with different numbers and types of functional pyridylalkylamino groups were synthesized by reactions of chlorophosphazenes with aminoalkylpyridine derivatives and completely characterized. The molecular structures of one multifunctional N-donor ligand, N 3 P 3 (OC 6 H 5 ) 5 (NHCH 2 CH 2 C 5 H 4 N-2) (1), was determined by X-ray structure analysis. The hexafunctionalized derivative N 3 P 3 (NHCH 2 CH 2 C 5 H 4 N-2) 6 (10) reacts with dichloromethane to form the HCl salt (10 a) the structure of which could also determined by X-ray crystal structure analysis. Complex formation of N 3 P 3 (OC 6 H 5 ) 5 (NHCH 2 C 5 H 4 N-3) (2) with cobalt(II) chloride yields the cobalt complex (2 a) in which two molecules of the ligand are bonded to the tetrahedraly coordinated cobalt atom by the pyridine nitrogen atoms. The tetra functionalized ligand gem-N 3 P 3 (OC 6 H 5 ) 2 -(NHCH 2 CH 2 C 5 H 4 N-2) 4 (8) forms the dinuclear cobalt-cobaltate complex (8 a) by interactions of a phosphazene nitrogen atom and the pyridine atoms of two cis-vicinal functional groups with a CoCl unit and a pyridine group with a CoCl 3unit.