Isolation of a Moderately Acidophilic Nitrobacter from a Nitrifying Community Supplied with Urea.

Nitrite-oxidizing bacteria (NOB), which perform the second step of aerobic nitrification, play an important role in soil. In the present study, we report a novel isolate from agricultural soil affiliated with the genus Nitrobacter and its physiological characteristics. We sampled the surface soil of a vegetable field and obtained mixed culture A31 using the most probable number (MPN) method with inorganic medium containing 0.

NAD levels in the rat primary cultured hepatocytes affected by peroxisome-proliferators.

The effect of peroxisome-proliferators (PPs) on the NAD level in primary cultured rat hepatocytes was investigated and compared with that in the liver of rat administered with PPs. Various PPs, including fibrates, phthalate esters and steroid, increased NAD level in the cultured hepatocytes as in whole animal with a little exception. The NAD level decreased after once reaching the peak by the addition of most PPs.

Effects of peroxisome-proliferators on the TRP-NAD pathway.

The mechanism of the elevation of hepatic NAD level in the rats administered clofibrate and other peroxisome-proliferators were investigated. In the hepatocytes from the clofibrate-fed rats, NAD biosynthesis from Trp, but not from nicotinic acid, was specifically stimulated. The activities of peroxisomal marker enzymes, the peroxisome-proliferator activated receptors (PPAR)-dependent enzymes and key enzymes in the Trp-NAD pathway changed in parallel with the hepatic NAD increase; the activity of quinolinate phosphori-bosyltransferase (QPRT) was increased whereas that of alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) was drastically reduced.

Peroxisome-proliferator regulates key enzymes of the tryptophan-NAD+ pathway.

Structually diverse peroxisome-proliferators (PPs) were investigated regarding their effects on NAD+ level and two key enzyme activities in the tryptophan (Trp)-NAD+ pathway in the liver of rats (Sprague-Dawley male) fed PP-containing diets freely for 2 weeks. All PPs, except for thyroxine, significantly increased hepatic NAD+ level in concert with hepatic hypertrophy. Activity of quinolinate phosphoribosyltransferase (QAPRTase), one of the key enzymes in the Trp-NAD+ pathway, was increased by the PPs which caused significant increase in the hepatic NAD+.

Synthesis of some pseudo-peptide analogs of thiol proteinase inhibitors.

Some pseudo-peptide analogs of thiol proteinase inhibitors were synthesized by a conventional solution method. Among them, Suc-Ala-Val-Val-Ala-psi-(CH2-NH)-Ala-pNA (peptide 1) and Suc-Ala-Val-Val-psi-(CH2-NH)-Ala-Ala-pNA (peptide 2) showed a stronger inhibitory activity compared with parent peptide such as Suc-Ala-Val-Val-Ala-Ala-pNA. In particular, peptide 2 was about 10-fold as active as the parent peptide (IC50 = 8 microM).