Isomerization of glyceraldehyde

Kinetics of isomerization of glyceraldehyde to dihydroxyacetone—and the formation of pyruvaldehyde from both—have been studied in sub- and super-critical water.191... 

Kinetics of isomerization of glyceraldehyde to dihydroxyacetone—and the formation of pyruvaldehyde from both— have been studied in sub- and super-critical water. Formaldehyde reacts with isoeugenol [l-(3-methoxy-4-hydroxyphenyl)propene] in alkaline medium to give a 1,3-dioxane derivative via an unusual Prins-type reaction. The potential-energy surface for the equihbriimi, HCO - - HCN H2CO - - CN, has been calculated by ab initio methods. 

Iron(III)hydroxide oxide [Fe(0H)0] has been shown to catalyze the condensation of 25-mM DL-glyceraldehyde to ketohexoses at 15 °C (pH 5-6). After 16 days 15.2% of sorbose, 12.9% of fructose, 6.1% of psicose, 5.6% of tagatose, and 2.5% of dendroketose are obtained. After 96 days at 15 °C this mixture was not decomposed. [Fe(0H)0] also catalyzes the isomerization of glyceraldehyde into dihydroxy acetone and of dihydroxy acetone into lactic acid [41]. 

Two features of this enzyme are noteworthy. First, TPI displays great catalytic prowess. It accelerates isomerization by a factor of 10 compared with the rate obtained with a simple base catalyst such as acetate ion. Indeed, the ratio for the isomerization of glyceraldehyde... 

Assary RS, Curtiss LA (2011) Theoretical study of 1,2-hydride shift associated with the isomerization of glyceraldehyde to dihydroxyacetone by lewis acid active site models. J Phys Chem A 115 8754-8760... 

The isomerization of glyceraldehyde [HOCH2CH(OH)CHO] to dihydroxyacetone at the surface of Lewis acidic zeolites has been studied theoretically, focusing on the rate-determining 1,2-hydride shift involved. ... 

The rate-limiting step for the isomerization of glyceraldehyde to dihydroxy acetone catalysed by the active site of Sn-beta zeolite is the [l,2]-hydride shift, which is enhanced by the active participation of the hydroxyl group in the hydrolysed Sn-beta active site. The activity of the catalysts are in the order of Sn > Zr > Ti > Si (Scheme 41). ... 

Scheme 11.4. The isomerization of glyceraldehyde 3-phosphate to dihydroxyacetone phosphate catalyzed by triosephosphate isomerase (EC 5.3.1.1) and through a common enol. It is presumed that proton abstraction (and readdition as the (pro-R) hydrogen) is affected by an active site giutamate anion.

Figure 3 A possible mechanism for the isomerization of dihydroxyacetone phosphate (DHAP) to D glyceraldehyde 3 phosphate (GAP) by the enzyme triosephosphate isomerase (TIM). The general acid (Glu 165) and general base (His 95) are shown.

The chiral (E)-oxazolone derived from 1,2-O-isopropyIidene-D-glyceraldehyde has also been used as a dienophile in the Diels-Alder reaction and, in this case, ( /Z) isomerization of the oxazolone can be avoided using heterogeneous catalysts that promote the synthesis of trans-adducts. ... 

Triose phosphate isomerase interconverts dihydroxyacetone phosphate and glyceraldehyde 3-phosphate (see Figure 8.16). Dihydroxyacetone phosphate must be isomerized to glyceraldehyde 3-phosphate for further metabolism by the glycolytic pathway. This isomerization results in the net production of two molecules of glyceraldehyde 3-phosphate from the cleavage products of fructose 1,6-bisphosphate. 

Step 5 is an isomerization of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate that occurs by keto-enol tautomerization. 

Stereoisomerism occurs in vinyl polymers when one of the carbon atoms of the monomer double bond carries two different substituents. It is formally similar to the optical isomerism of organic chemistry in which the presence of an asymmetric carbon atom produces two isomers which are not superimposable. Thus glyceraldehyde exists as two stereoisomers with configurations shown in 4-13. (The dotted lines denote bonds below and the wedge signifies bonds above the plane of the page.) Similarly, polymerization of a monomer with structure... 

Much is known about the catalytic mechanism of triose phosphate isomerase. TIM catalyzes the transfer of a hydrogen atom from carbon 1 to carbon 2 in converting dihydroxyacetone phosphate into glyceraldehyde 3-phosphate, an intramolecular oxidation-reduction. This isomerization of a ketose into an aldose proceeds through an enediol intermediate (Figure 16.6). 

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