Synthesis and biosynthesis of alkoxylipids.

Chromatographic methods have shown that lipids with long alkyl or 1-alkenyl chains–called alkoxylipids or ether lipids–are widely distributed in human and animal tissues. These compounds comprise neutral alkoxylipids, i. e. 1-O-alkyl or 1-O-(1-alkenyl)-2,3-di-O-acylglycerols, and alkoxylipids which are linked by a phosphate residue at C-3 to aminoethanol, choline or serine. 1-O-Alkylglycerols, 1-O-(1-alkenyl)glycerols and other natural alkoxylipids can be synthesized in high yields. 2-Alkyl, 1,3-dialkyl and trialkylglycerols which are not found in nature are also accessible by synthesis. The neutral alkoxylipids are employed in biomedical investigations, e.g. as substrates in acyl-hydrolase systems or in fat absorption studies. The principal features of alkoxylipid biosynthesis have been elucidated. The alkyl residue is derived from a saturated or monounsaturated fatty acid via the corresponding alcohol. 1-O-(1-alkenyl)-2-O-acylglycerophosphoryl aminoethanols (“plasmalogens”) are apparently formed from the appropriate 1-alkyl compounds; this is not possible in the case of the choline series. Both “aminoethanol” and “choline” plasmalogens are, nevertheless, present in most tissues.     

Inhibitors of prostaglandin biosynthesis from Dalbergia odorifera.

The root heartwood of Dalbergia odorifera T. Chen (Leguminosae) is a Chinese medicinal drug (Japanese name koshinko) used for a stagnant blood syndrome (stagnation of disordered blood; Japanese, oketsu). In addition to 10 known compounds, five new phenolic compounds, isomucronustyrene and hydroxyobtustyrene (cinnamylphenols), (+)-isoduartin (isoflavan), odoriflavene (isoflav-3-ene) and (-)-odoricarpan (pterocarpan) were isolated and their structures were elucidated on the basis of chemical and spectroscopic methods. Of the fifteen compounds isolated, cinnamylphenols, isoflavans, isoflavene and benzoic acid derivative significantly inhibited prostaglandin biosynthesis as well as platelet aggregation induced by arachidonic acid.     

青蒿素生物合成的研究1. 青蒿素体内青蒿酸的生物合成

应用幼苗水培法或顶株扦插法, 在青蒿植株体内以[2-^1^4c]-3,5-二羟基-3-甲基戊酸-δ-内酯([2-^1^4C]-MVA)为前体, 成功地生物合成了青蒿酸(3).     

Studies on the biosynthesis of arteannuin. IV. The biosynthesis of arteanniuin and arteannuin B by the leaf homogenate of Artemisia annua L.

Arteannuic acid and (-)11R,13-dihydroarteannuic acid are the key intermediates in the biosynthesis of arteannuin by the leaf homogenate of Artemisia annua L., and arteannuic acid and epoxyarteannuic acid are the intermediates of arteannuin B. and epoxyarteannuic acid can not be transformed into arteannuin by the homogenate.     

Toward the pathway of S. aureus WTA biosynthesis

Wall teichoic acid (WTA) contributes profoundly to the virulence of Staphylococcus aureus. The successful in vitro reconstitution of poly-ribitolphosphate WTA biosynthesis using recombinant enzymes sheds new light on WTA enzymology and paves the way for developing new antibiotics that target WTA biosynthesis, as discussed in Brown et al. in a recent issue of Chemistry & Biology.     

Investigations of coronatine biosynthesis. Overexpression and assay of CmaT, a thioesterase involved in coronamic acid biosynthesis

The protein (CmaT) encoded by the cmaT gene of the coronamic acid biosynthetic gene cluster has been overexpressed in Escherichia coli in soluble and active form fused to the carboxyl terminus of MalE, the maltose-binding protein. CmaT was also overexpressed in E. coli as an N-terminal His-tagged protein. The N-terminal His-tagged form of CmaT was produced in insoluble form, but it could be refolded to obtain CmaT in soluble and highly active form. Both the MalE-CmaT fusion protein and the refolded His-tagged CmaT protein exhibited esterase activity.     

Mechanism of presqualene pyrophosphate-squalene biosynthesis II. Synthesis of bifarnesol

A convenient synthesis of the racemate of bifarnesol (4), a proposed biochemical precursor of presqualene pyrophosphate and squalene, is described.     

Shikimate-derived metabolites. 10. Synthetic studies on the biosynthesis of para-aminobenzoic acid.

The total synthesis of $\text{trans}$-4-amino-3-hydroxycyclohexa-1,5-diene carboxylic acid $\text{7}$, an hypothetical intermediate in the biosynthesis of $\text{p}$-aminobenzoic acid, has been achieved.     

Protein biosynthesis: the codon-specific activation of amino acids.

At the start of protein biosynthesis the amino acids are chemically activated by esterification with transfer ribonucleic acids bearing the appropriate anticodons. The esterification is catalyzed with an exceptionally high specificity by aminoacyl-tRNA synthetases. Current knowledge of the structural properties of the reactants, the course of the reaction, and the reasons for its specificity are summarized.