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ketol การใช้

ประโยคมือถือ
  • The enzyme is a hexamer, forming the largest structurally known ketol isomerase, and has no residues.
  • It is an ?-hydroxyketone, also called a ketol, and is the simplest hydroxy ketone structure.
  • Working in DMSO solvent does not allow isolation of the bicyclic ketol intermediate, it leads directly to the optically active bicyclic dione.
  • Hall LS, Gordon G . Grigg, Craig Moritz, Besar Ketol, Isa Sait, Wahab Marni and M . T . Abdullah . 2004.
  • The starting material is an achiral triketone and it requires just 3 % of proline to obtain the reaction product, a ketol in 93 % enantiomeric excess.
  • Thus, they could isolate the optically active 6, 5-bicyclic ketol described so far only in the Hajos-Parrish publications [ 1 ], [ 2 ].
  • The " ilvBNC " operon, which encodes ALS I and a ketol-acid reductoisomerase, is similarly regulated, but is specific to isoleucine and leucine; valine does not affect it directly.
  • In this patent, the isolation and characterization of the above pictured optically active intermediate bicyclic ketol ( in parentheses ) has also been described, because they worked at ambient temperature in anhydrous dimethylformamide ( DMF ) solvent.
  • Overexpression of the four genes encoding non-oxidative pentose phosphate pathway enzymes Transaldolase, Transketolase, Ribulose-5-phosphate epimerase and Ribose-5-phosphate ketol-isomerase led to both higher D-xylulose and D-xylose fermentation rate.
  • As shown above, Hajos and Parrish worked at ambient temperature in dimethylformamide ( DMF ) solvent using a catalytic amount ( 3 % molar equiv . ) of ( S )-(  " )-proline enabling them to isolate the optically active intermediate bicyclic ketol.
  • Similar studies of the 7a-ethyl-homologue showed that the ethyl bicycic ketol existed in a cis conformation in which the 7a-ethyl group is equatorially oriented and the hydroxyl group is axially oriented in the chair form of the six-membered ring as shown above.
  • The top side approach results in the formation of an enantiotopic carbinolamine to give the (  " )-( 3aR, 7aR )-3a, 4, 7, 7a-tetrahydro-3a-hydroxy-7a-methyl-1, 5 ( 6H )-indanedione bicyclic ketol enantiomer identical to the one obtained with unnatural ( R )-( + )-proline.
  • The Schering group worked under non biological conditions using ( S )-Proline ( 47 mol % ), 1N perchloric acid, in acetonitrile at 80 癈 . Hence, they could not isolate the Hajos, Parrish intermediate bicyclic ketol but instead the condensation product ( 7aS )-7a-methyl-2, 3, 6, 7-tetrahdroindol-1, 5-dione through the loss of water.
  • PGE2 and PGE1 are 20 carbon metabolites of arachidonic acid and dihomo-?-linolenic acid, respectively, with a double bond between carbons 13 and 14, a carbon-carbon bond between carbons 8 and 12 ( which establishes their cyclopentanone structure ), hydroxyl residues at carbons 11 and 15, and a ketol residue at carbon 9 . They differ in that PGE2 has, while PGE1 lacks, a double bound between carbons 5 and 6.