Biosynthesis and production of quercitols and their application in the production of pharmaceuticals: current status and prospects.

(-)-vibo-Quercitol is a deoxyinositol (1L-1,2,4/3,5-cyclohexanepentol) that occurs naturally in low concentrations in oak species, honeydew honey, and Gymnema sylvestre. The author's research group recently reported that (-)-vibo-quercitol and scyllo-quercitol (2-deoxy-myo-inositol, 1,3,5/2,4-cyclohexanepentol), a stereoisomer of (-)-vibo-quercitol, are stereoselectively synthesized from 2-deoxy-scyllo-inosose by the reductive reaction of a novel (-)-vibo-quercitol 1-dehydrogenase in Burkholderia terrae and of a known scyllo-inositol dehydrogenase in Bacillus subtilis, respectively. The author's research group therefore identified two enzymes capable of producing both stereoisomers of deoxyinositols, which are rare in nature. (-)-vibo-Quercitol and scyllo-quercitol are potential intermediates for pharmaceuticals. In this review, the author describes the biosynthesis and enzymatic production of quercitols and myo-inositol stereoisomers and their application in the production of potential pharmaceuticals.

Discovery and utilization of biocatalysts for chiral synthesis: an overview of Chinese scientists' research and development.

The importance of chiral issues in active pharmaceutical ingredients has been widely recognized not only by pharmacologists, but also by chemists, chemical engineers and administrators. In fact, the worldwide sales of single-enantiomer drugs have exceeded US $150 billion. Among them the contribution rate of biocatalysis technology is ever increasing (up to 15-20%). This chapter will focus on the biocatalytic synthesis of chiral compounds useful for pharmaceutical industry. Diverse enzymes, such as oxidoreductases, epoxide hydrolases, nitrilases/nitrile hydratases and hydroxy nitrile lyases which were isolated from various sources including microorganisms and plants, and the methodology for utilizing these enzymes in enantioselective or asymmetric synthesis will be discussed briefly.

Laccase and other ligninolytic enzyme activities of selected strains of Trametes spp. from different localities and substrates.

Eighty-three strains belonging to three species of the genus Trametes FR. (T. versicolor, T. hirsuta and T. ochracea) collected in different localities and on different substrates were screened for laccase production. The production of other lignin-modifying enzymes--manganese peroxidase (MnP) and lignin peroxidase (LiP)--and the decolorization ability were also determined in 21 of them. Production variability was relatively high and no significant correlation was found between the origin of the strains (locality, substrate) and the enzyme production. Dikaryons of all 3 species (but not of all their strains) exhibited LiP activity, which was not detected in the respective monokaryons.

Characterization of hydrogenase II from the hyperthermophilic archaeon Pyrococcus furiosus and assessment of its role in sulfur reduction.

The fermentative hyperthermophile Pyrococcus furiosus contains an NADPH-utilizing, heterotetrameric (alphabetagammadelta), cytoplasmic hydrogenase (hydrogenase I) that catalyzes both H(2) production and the reduction of elemental sulfur to H(2)S. Herein is described the purification of a second enzyme of this type, hydrogenase II, from the same organism. Hydrogenase II has an M(r) of 320,000 +/- 20,000 and contains four different subunits with M(r)s of 52,000 (alpha), 39,000 (beta), 30,000 (gamma), and 24,000 (delta). The heterotetramer contained Ni (0.9 +/- 0.1 atom/mol), Fe (21 +/- 1.6 atoms/mol), and flavin adenine dinucleotide (FAD) (0.83 +/- 0.1 mol/mol). NADPH and NADH were equally efficient as electron donors for H(2) production with K(m) values near 70 microM and k(cat)/K(m) values near 350 min(-1) mM(-1). In contrast to hydrogenase I, hydrogenase II catalyzed the H(2)-dependent reduction of NAD (K(m), 128 microM; k(cat)/K(m), 770 min(-1) mM(-1)). Ferredoxin from P. furiosus was not an efficient electron carrier for either enzyme. Both H(2) and NADPH served as electron donors for the reduction of elemental sulfur (S(0)) and polysulfide by hydrogenase I and hydrogenase II, and both enzymes preferentially reduce polysulfide to sulfide rather than protons to H(2) using NADPH as the electron donor. At least two [4Fe-4S] and one [2Fe-2S] cluster were detected in hydrogenase II by electron paramagnetic resonance spectroscopy, but amino acid sequence analyses indicated a total of five [4Fe-4S] clusters (two in the beta subunit and three in the delta subunit) and one [2Fe-2S] cluster (in the gamma subunit), as well as two putative nucleotide-binding sites in the gamma subunit which are thought to bind FAD and NAD(P)(H). The amino acid sequences of the four subunits of hydrogenase II showed between 55 and 63% similarity to those of hydrogenase I. The two enzymes are present in the cytoplasm at approximately the same concentration. Hydrogenase II may become physiologically relevant at low S(0) concentrations since it has a higher affinity than hydrogenase I for both S(0) and polysulfide.