Structures of two haptotropic isomers generated by the sliding of 1,3,5-triene ligands on a Pd-Pd-Pd chain

Two haptotropic isomers of [Pd(3)(mu(3)-DMVC)(2)(CH(3)CN)(2)][BF(4)](2) (DMVC = 1,2-di-(E)-carbomethoxyvinylcyclopentene) were structurally determined by X-ray crystallographic analyses; a monoclinic crystal contained a symmetric sandwich complex (mu(3)-eta(2):eta(2):eta(2)-coordination of DMVC ligands) and a triclinic crystal contained an unsymmetric sandwich complex (mu(3)-eta(2):eta(3):eta(1)-coordination of DMVC ligands), where the latter are connected to each other by C-HO hydrogen bonds.     

A stable zerovalent palladium chain enveloped by a pi-electron sheath of conjugated polyene ligands

A surprisingly stable homoleptic Pd(0)(4) chain complex of non-activated olefins was isolated and structurally characterized by X-ray crystallographic analysis, and the unique structure and bonding are compared to those of the corresponding dicationic [Pd(4)](2+) chain sandwich complex.     

Photocatalytic degradation of adenosine triphosphate in an aqueous suspension of TiO<Subscript>2</Subscript>: a HPLC and <Superscript>1</Superscript>H-NMR study

Photocatalytic degradation process of ATP was followed by HPLC and ¹H-NMR measurements. Adenine was one of the major products when the aqueous ATP sample with TiO₂ dispersion was irradiated by UV light (λ = 365 nm) for 90 min. The ¹H-NMR spectra indicated the presence of another product (Z), which likely came from the ribose moiety in ATP. Photocatalytic generation of OH^˙ radicals on TiO₂ surface was concluded to be responsible for degrading ATP. A working hypothesis of the reaction process was proposed to account for the reaction products.     

Measurements of kineic parameters of inorganic pyrophosphatase by flow-injection procedures

Two flow-injection systems were designed for characterizing the enzymatic hydrolysis of pyrophosphate by inorganic pyrophosphatase (EC 3.6.1.1). By using a molybdenum(VI) reagent the selective determination of a product, orthophosphate, in the presence of pyrophosphate was made. An anion exchange column was employed for the simultaneous determination of both the substrate and the product with a molybdenum(V)/molybdenum(VI) reagent. The effects of magnesium concentration and reaction temperature on the enzyme activity were determined. The Michaelis constant and maximum velocity at 25°C and pH 7.2 were evaluated. K_m was ca. 3 μM.     

Estimation of molecular weights of peptides by determination of height equivalent to a theoretical plate in size-exclusion chromatography

The analysis of the flow-rate required to obtain the optimum height equivalent to a theoretical plate, HETP, has been used to estimate the molecular weight, MW, of peptides in size-exclusion chromatography. A straight line is obtained when log MW is plotted against the flow-rate which gives the optimum HETP. This relationship holds even for peptides which adsorb to column packings. The typical quantity of peptide required is 1 nmol and analysis time was less than 2 h. The method is applied to peptides of 200–10,000, and the precision is ±20%. The method may be applicable to the analysis of MW for all classes of compounds.