Production of aliphatic aldehydes on peroxidation of various types of lipids.

IN vitro peroxidation by air, or xanthine-xanthine oxidase (xanthine-XOD) was performed to estimate the production of aliphatic aldehydes from free polyunsaturated fatty acids (PUFA), triglycerides, phospholipids and rat liver microsomes and mitochondria. The aldehyde contents in peroxidized lipids were determined by liquid chromatography and fluorescence detection. In both peroxidation, pentanal, (E)-4-hydroxy-2-nonenal (4-HN), and hexanal were produced from omega-6 PUFA rich lipids and propanal was markedly enhanced by increasing the degree of fatty acid unsaturation. The ratios of 4-HN to hexanal production in xanthine-XOD peroxidation of the omega-6 PUFA rich lipids, and rat liver microsomes and mitochondria were much higher than those in air peroxidation. The ratios (4-HN/hexanal) obtained in microsomes and mitochondria by xanthine-XOD were similar to those in rat liver observed in vitamin E deficient studies. The determination of these aldehydes may be useful to estimate the kinds of fatty acids peroxidized and investigate in vivo lipid peroxidation mechanism.     

An in vitro screening method for DNA cytosine-C5-methylase inhibitor

A specific inhibitor of DNA cytosine C5-methylases would be useful for studying genomic imprinting, X-chromosome inactivation, carcinogenesis, and regulation of tissue-specific gene expression, for these physiological phenomena appears to be regulated through DNA methylation in promoter sequences. This paper reports a novel convenient in vitro assay method for screening DNA cytosine C5-methylase inhibitor. Our method uses a commercially available Hae III methylase (cytosine C5 methylase), its corresponding Hae III endonuclease, and lambda DNA as their substrate.     

Mössbauer spectroscopic studies on mixed-valence states in trinuclear iron carboxylates

Mixed-valence states of iron atoms in newly synthesized mixed-valence trinuclear iron carboxylate complexes with -bonding ligands, such as acrylate, diphenylacetate, 1-naphthylacetate, and cyclohexylacetate which has no -bonding, were studied by means of Mössbauer spectroscopy. The cyclohexylacetate complex shows a temperature-dependent valence delocalization, while the 1-naphthylacetate complex shows temperature-independent mixed-valence states. The acrylate and diphenylacetate complexes show temperature-dependent mixed-valence states, although they do not reach an averaged-valence state at room temperature.