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Arachidonate 5-lipoxygenase initiates the biosynthesis of leukotrienes which are known as mediators of inflammation and anaphylaxis. The enzyme was highly purified from the cytosol fraction of porcine leukocytes by immunoaffinity chromatography using a monoclonal antibody raised against a crude enzyme preparation .The purified enzyme showed the leukotriene A synthase activity (5-hydroperoxy acid → 5-hydroperoxy acid). Several lines of enzymological finding confirmed that both activities were attributed to the same enzyme protein .The enzyme also oxygenated the 6-position of 5-hydroperoxy acid, and catalyzed the lipoxin formation. Immunohistochemical study with anti-5-lipoxygenase antibody showed the localization of the enzyme in the cytosol of porcine neutrophils, eosinophils and mast cells but not in lymphocytes. Furthermore, bronchiolar epithelial cells and pancreatic acinar cells were positively stained.

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The in vitro effect of L-ascorbic acid on bacteria was investigated using a wide variety of bacteria (30 strains). In the presence of a trace level of Cu^<2+>, L-ascorbic acid exerted a strong killing effect on Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Proteus morganii, Proteus vulgaris, Pseudomonas phaseolicola, Salmonella typhimurium, Serratia marcescens and Staphylococcus aureus. It excerted a moderate effect on Brevibacterium lactofermentum and Lactobacillus plantarum. On the other hand, it excerted no effect on Bacillus cereus, Corynebacterium glutamicus, Lactobacillus casei, Micrococcus flavus and Sarcina lutea. Also, the effect of L-ascorbic acid on yeasts was investigated using selected yeasts (8 strains ). It excerted no effect on Hansenula anomala, Pichia membranaefaciens, Rhodotorula rubra, Saccharomyces cerevisiae, Saccharomyces rouxii, Schizosaccharomyces octospolus and Sporobolomyces salmonicolor. The results indicate that L-ascorbic acid exerts a killing effect on a number of bacteria, procaryotic cells, but do not exert a killing effect on yeasts, eucaryotic cells. There were little differences in the killing effect between L-ascorbic acid and D-isoascorbic acid. This indicates that the effect is independent of the stereoisomerism with inversion of the hydroxyl group at C-5 of ascorbic acids.

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Nicotinamide methyltransferase (EC 1.1.1.1) was purified from rat liver. The purification was conducted by ammonium sulfate fractionation and column chromatographies on DE 52, Butyl Toyopearl and Sephadex G-100. As the results, the enzyme was purified up to 254-fold with a yield of 11 %. The enzyme of Butyl Toyopearl fraction is stable, so this enzyme preparation was used for the determination of S-adenosyl-L-methionine (SAM). The enzymatic properites of the preparation were as follows : optimum temperature, 34.7℃; optimum pH, 5.9; K_m values for nicotinamide and SAM, 61.7 μM and 10.6 μM, respectively ; inhibitors, isonicotinamide, picolinamide, benzamide, 3-aminopyridine, salicylamide (all were competitive to nicotinamide), N^1-methyl-nicotinamide, S-adenosyl-L-homocysteine (product inhibition was observed with both substrates), PCMB, heavy metal ions, etc. The regression line for the determination of SAM with the enzyme reaction was linear until 600 pmol with a correlation coefficient of 0.998. The SAM contents in various samples were determined with this method. The high contents were observed in Lactobacillus plantarum, Escherichia coli, baker's yeast, tomato, etc. The possibility for the determination of SAM by this method in various samples was suggested.

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