Polyhydroxybutyrate , synthesis

The three step pathway of polyhydroxybutyrate synthesis (PHB) as found in Ralstonia eutropha. 

Wrobel M, Zebrowski J, Szopa J (2004) Polyhydroxybutyrate synthesis in transgenic flax. J Biotechnol 107(l) 41-54... 

Gu P, KangJ.Yang F, Wang Q, Liang Q, Qi Q.The improved 1-tryptophan production in recombinant Escherichia coli by expressing the polyhydroxybutyrate synthesis pathway. Appl Microbiol Biotechnol 2013 97 4121-7. 

Zhang J, Hao N, Chen GQ. Efect of expressing polyhydroxybutyrate synthesis genes (phbCAB) in Streptococcus zooepidemicus on production of lactic acid and hyaluronic acid. Appl Microbiol Biotechnol 2006 71 222-7. 

Lai W, Chen G. Polyhydroxybutyrate synthesis in recombinant Zymonomas mohilis affected ethanol production. Chin Biotechnol 2006 26 56. 

This review will focus on the synthesis of polyhydroxybutyrate (poly(3HB)) and PHA co-polymers in plants. Most of the knowledge on PHAs, including the... 

The preparation of enantiomerically pure chemicals is also the theme of the next group of four procedures. The biopolymer polyhydroxybutyric acid, which is now produced on an industrial scale, serves as the starting material for the large scale synthesis of (R)-3-HYDROXYBUTANOIC ACID and (R)-METHYL 3-HYDROXYBUTANOATE. Esters of (-)-camphanic acid are useful derivatives for resolving and determining the enantiomeric purity of primary and secondary alcohols. An optimized preparation of (-)-(1S,4R)-CAMPHANOYL CHLORIDE is provided. The preparation of enantiomerically pure a-hydroxyketones from ethyl lactate is illustrated in the synthesis of (3HS)-[(tert)-BUTYL-DIPHENYLSILYL)OXY]-2-BUTANONE. One use of this chiral a-hydroxyketone is provided in the synthesis of (2S,3S)-3-ACETYL-8-... 

AcetoacetylCoA thiolase (E.C. 2.3.1.9), acetoacetylCoA reductase (E.C. 1.1.1.36), and polyhydroxybutyrate synthetase12471 are the enzymes involved in polyester synthesis. AcetoacetylCoA thiolase catalyzes the head-to-tail Claisen condensation of two acetylCoA molecules. In this reaction, the active site cysteine attacks acetylCoA to form a thioester enzyme intermediate, which then reacts with the enolate derived from enzymatic deprotonation of the other acetylCoA. Mechanistic studies have been performed on this enzyme from Zooglea ramigera, which has been cloned and overexpressed12471. It has been established that the thiolase will form acyl enzyme intermediates with a number of acylCoA substrates, but will only accept acetylCoA as the nucleophile. After subsequent reduction, this results in all polymer units possessing a P-hydroxy group. These polymers are also useful sources of (R)-P-hydroxy acids[2481. 

Anderson, A., Williams, D., Taidi, B., Dawes, E. and Ewing, D., 1992, Studies on copolyester synthesis by Rhodococus ruber and factors influencing the molecular mass of polyhydroxybutyrate accumulated by methylobacterium extorquens and Alcaligenes eutrophus. FEMSMicrobiol. Rev., 103 93-102. 

York GM, Stubbe J, Sinskey AJ (2002) The Ralstonia eutropha PhaR protein couples synthesis of the PhaP phasin to the presence of polyhydroxybutyrate in cells and promotes polyhydroxybutyrate production. J Bacteriol 184 59-66... 

Aral Y, Nakashita H, Doi Y, Yamaguchi 1 (2001) Plastid targeting of polyhydroxybutyrate biosynthetic pathway in tobacco. Plant Biotechnol 18 289-293 Arai Y, Nakashita H, Suzuki Y, Kobayashi Y, Shimizu T, Yasuda M, Doi Y, Yamaguchi I (2002) Synthesis of a novel class of polyhydroxyalkanoates in Arabidopsis peroxisomes, and their use in monitoring short-chain-length intermediates of P-oxidation. Plant Cell Physiol 43 555-562... 

York GM, Stubbe J, Sinskey AJ (2001) New insight into the role of the PhaP phasin of Ralstonia eutropha in promoting synthesis of polyhydroxybutyrate. J Bacteriol 183 2394-2397 Yuste L, Hervas AB, Canosa I, Tobes R, Jimenez Jl, Nogales J, Perez-Perez MM, Santero E, Diaz E, Ramos JL, de Lorenzo V, Rojo F (2006) Growth phase-dependent expression of the Pseudomonas putida KT2440 transcriptional machinery analysed with a genome-wide DNA microarray. Environ Microbiol 8 165-177... 

Polyhydroxyalkanoates, Polyhydroxybutyrate, History, Bacterial synthesis. Chemical synthesis. Genetic engineering. Mechanical properties. Thermal transitions. Crystallization, Plasticizers, Thermal degradation. Processing, Applications... 

Some natural polyesters, such as polyhydroxybutyrate, are commercial products of micro-organisms. Outside of the cell the enzymatic synthesis of high-molecular-weight polyesters may be impractical on any sensible scale, but the synthesis of smaller blocks with a molecular weight of several thousand is practical. The ester bond is formed under conditions where water activity is low, and the concentrations of alcohol and carboxylic acids are high. The reaction (Scheme 6.28), which is a transesterification between... 

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