l-Rhamnose is a component of plant cell wall pectic polysaccharides, diverse secondary metabolites, and some glycoproteins. The biosynthesis of the activated nucleotide-sugar form(s) of rhamnose utilized by the various rhamnosyltransferases is still elusive, and no plant enzymes involved in their synthesis have been purified. In contrast, two genes (rmlC and rmlD) have been identified in bacter...

The tumor promoters, 12-O-tetradecanoylphorbol-13-acetate (TPA), phorbol-12,13-didecanoate, teleocidin, and dihydroteleocidin, at nM levels, but not the non-tumor-promoting 4 alpha-phorbol-12,13-didecanoate even at microM concentrations, stimulated arachidonic acid metabolism in cultured rat liver cells. These liver cells synthesize primarily prostaglandin I2 [measured as its nonenzymatic hydro...

The various neutral amino acids and aliphatic 2-keto acids exhibit differential effects on insulin secretion. The common denominator for all these effects is the 2-ketoglutarate generation in the pancreatic B-cell mitochondria. The neutral amino acids L-leucine and L-norvaline and the aliphatic ketomonocarboxylic acids 2-ketoisocaproate, 2-ketocaproate, 2-ketovalerate, and 2-keto-3-methylvalera...

For some years evidence that 2-keto-D-gluconic acid is implicated in a number of biochemical systems, notably in Acetobacter species (Bernhauer & Gorlich, 1935; Kulka & Walker, 1954) and in Pseudomonas species (Lockwood, Tabenkin & Ward, 1941; Norris & Campbell, 1949) has been accumulating. Studies by Warburg & Christian (1937) with red blood cells, by Lipmann (1936) with yeast macerate prepara...

Endogenously released or exogenously administered glucocorticosteroids are relevant hormones for controlling inflammation. Only 11beta-hydroxy glucocorticosteroids, but not 11-keto glucocorticosteroids, activate glucocorticoid receptors. Since we found that glomerular mesangial cells (GMC) express 11beta-hydroxysteroid dehydrogenase 1 (11beta-OHSD1), which interconverts 11-keto glucocorticoster...

M01A82W, M11A82W and M01A82WS72I are three cytochrome P450 BM3 (CYP102A1) variants. They can catalyze the hydroxylation of testosterone (TES) and norethisterone at different positions, thereby making them promising biocatalysts for steroid hydroxylation. With the aim of obtaining more hydroxylated steroid precursors it is necessary to probe the steroidal substrate diversity of these BM3 variant...

Metabolism and renal excretion of valproic acid (VPA) were examined in maternal, fetal, and newborn sheep to identify the underlying reasons for the previously observed reduced VPA clearance in newborn lambs. Plasma and urine from VPA infusion studies in maternal, fetal, and newborn sheep were analyzed for VPA and its metabolites [VPA-glucuronide; beta-oxidation products: (E)-2-ene, (E)-3-ene, ...

We studied the effects of plasma high density and low density lipoproteins upon the synthesis of prostacyclin and prostaglandin E2 by vascular smooth muscle cells. Prostaglandin synthesis was measured in 24-hour cultures by radioimmunoassay of the stable metabolites of prostacyclin, 6-keto-prostaglandin F1 alpha and of prostaglandin E2. High density lipoproteins induced dose-dependent increases...

UDP-xylose synthase (UXS) catalyzes decarboxylation of UDP-D-glucuronic acid to UDP-xylose. In mammals, UDP-xylose serves to initiate glycosaminoglycan synthesis on the protein core of extracellular matrix proteoglycans. Lack of UXS activity leads to a defective extracellular matrix, resulting in strong interference with cell signaling pathways. We present comprehensive structural and mechanist...

Recent research has resulted in considerable modification of the earlier concept that enzymatic transamination was limited to reactions between alanine, aspartate, glutamate, and their or-keto analogues. Reactions leading to the reversible amination of the cY-keto analogues of many of the natural amino acids have been described (l-5), and there is also evidence that aldehyde groups may particip...