Acetaldehyde phosphorylation

The next stage leads to the transformation of the phosphorylated glyceric acid into pyruvic add, which is then converted into acetaldehyde and C02 by the enzyme carboxylase. As soon as the acetaldehyde is formed it enters into enzymic reaction with the phosphorylated glycer-aldehyde which is dehydrogenated to the acid while the aldehyde becomes ethyl alcohol. 

Atkinson KJ and Rao RK [2001] Role of protein tyrosine phosphorylation in acetaldehyde-induced disruption of epithelial tight junctions. Am J Physiol 280 G1280-G1288... 

The substrate in most reactions of this type is an alcohol, which becomes oxidized to an aldehyde or ketone, e.g. ethanol is oxidized to acetaldehyde. Some reactions employ the alternative phosphorylated cofactor NADP+ the phosphate does not function in the oxidation step, but is merely a recognition feature helping to bind the compound to the enzyme. The full structures of NAD+ and NADP+ are shown in Box 11.1. 

In contrast to transketolase and the DHAP-dependent aldolases, deoxyribose aldolase (DERA) catalyzes the aldol reaction with the simple aldehyde, acetaldehyde. In vivo it catalyzes the formation of 2-deoxyribose-5-phosphate, the building block of DNA, from acetaldehyde and D-glyceraldehyde-3-phosphate, but in vitro it can catalyze the aldol reaction of acetaldehyde with other non-phosphorylated aldehydes. The example shown in Scheme 6.28 involves a tandem aldol reaction... 

This reaction is considered in Sections 5.2.3, p. 496, and 5.18.2, p. 799, and the specific examples that are included in this section are (i) the formation of ethyl cyclohexylideneacetate from cyclohexanone and triethyl phosphonoacetate in the solvent 1,2-dimethoxyethane and using sodium hydride as the base for the formation of the phosphoryl-stabilised anion 254 and (ii) the formation of ethyl (E)-but-2-enoate from acetaldehyde and triethyl phosphonoacetate under PTC conditions255 (Expt 5.215). In the latter example the (E configuration is to be expected from the general features of the reaction that are summarised in Section 5.2.3, p. 496. 

Razumov, A.I., Sokolov, M.P., Zykova, T.V, Liorber, B.G.. Savicheva, G.A., and Salakhutdinov, R.A., Reactivity and structure of phosphorylated carbonyl compounds. Part 9. Aldo-enol equihbrium of phosphorylated acetaldehydes, Zh. Obshch. Khim., 42, 47, 1972 J. Gen. Chem. USSR (Engl. Transl.), 42, 43, 1972. 

In weakly acid media, the coupling of diethoxyphosphinyl-acetaldehyde and aryldiazonium salts yields the phosphorylated glyoxal a-arylhydrazones (318) as the principal products with the phosphorylated formazans (319) as minor products. With an excess of diazonium salt, or when pyridine is used as the... 

Ethanol is a dietary fuel that is metabolized to acetate principally in the liver, with the generation ofNADH. The principal route for metabolism of ethanol is through hepatic alcohol dehydrogenases, which oxidize ethanol to acetaldehyde in the cytosol (Fig. 25.1). Acetaldehyde is further oxidized by acetaldehyde dehydrogenases to acetate, principally in mitochondria. Acetaldehyde, which is toxic, also may enter the blood. NADH produced by these reactions is used for adenosine triphosphate (ATP) generation through oxidative phosphorylation. Most of the acetate enters the blood and is taken up by skeletal muscles and other tissues, where it is activated to acetyl CoA and is oxidized in the TCA cycle. 

Damage to mitochondria from acetaldehyde and free radicals perpetuates a cycle of toxicity (see Fig. 25.7, circles 3 and 4). With chronic consumption of ethanol, mitochondria become damaged, the rate of electron transport is inhibited, and oxidative phosphorylation tends to become uncoupled. Fatty acid... 

The reaction between carbanion and a formamide, R2NCHO [R = Me or R2 = 0(CH2CH2)2] yields a complex (Scheme 60, which again, depending on the hydrolysis medium, may be hydrolysed to jS-phosphorylated acetaldehyde (611) or to the enamine 612, and as before, 612 may be acidolysed to Azeotropic removal of water... 

Salts of 1-nitroalkanes react with j -phosphorylated acetaldehydes to yield dialkyl (2-hydroxy-3-nitroalkyl)phosphonates or analogous phosphinates (Scheme 8). ... 

The cycloaddition of an arylnitrile oxide to methyl ethynylmethylphosphinate in an inert solvent at 5 °C produces a (5) -phosphinoylated-isoxazole 513 in high yield " and phosphorylated 1,2,4-oxadiazoles 514 are obtainable in a similar addition to (R0)2P(Z)CN (Z = O or Phosphorylated nitrile oxides, e.g. 515, are generally prepared by the Et3N-dehydrobromination of the product from the bromination of the oxime of a j5-(dialkoxyphosphinoyl)acetaldehyde, and then used in situ in reactions with alkenes to give isoxazolines and with alkynes to give isoxazoles . The chlorination and subsequent dehydrochlorination of diethyl (nitromethyl)phosphonate yield the nitrile oxides 516 (R = EtO Pr O or morpholinyf and these, with unsaturated centres, yield isomerically phosphorylated isoxazolines and isoxazoles. 

For optimization of DR5P production from the enzymatically prepared FDP and acetaldehyde with deoxyriboaldolase-expressing E. coli 10B5/pTS8, surfactants xylene and polyoxyethylene laurylamine (PL) were added for improvement of the permeation of phosphorylated compounds [10]. Under the preparative reaction... 

Alcoholism. Many investigations showed that alcoholism modulates the level of PTM-like phosphorylation [47], Alcohol consumption was shown to decrease the sialic acid conjugation to transferrin, an important carrier protein secreted from the liver to blood and other glycoproteins. This observation led to the development of a laboratory test for chronic alcohol use. Similar studies showed that direct production of alcohol metabolism (alpha-hydroxyethyl radicals, acetaldehyde and lipid peroxides) causes PTM that correlates with alcohol consumption in animal models and human subjects [48]. 

Acetaldehyde reduced bovine bronchial epithelial cell ciliary motility by inhibiting cAMP-mediated phosphorylation (Wyatt et al. 1997). When cihary axonemata were phosphorylated in vitro, 1 mM acetaldehyde (a subciliastatic concentration) inhibited the cAMP-dependent phosphorylation of a 38 kDa phosphoprotein. 

Thiamine, biotin, pantothenic acid, riboflavin and vitamin B12 are involved in propionic acid fermentation. Biotin forms the prosthetic group of methyl-malonyl-CoA transcarboxylase pantothenate is a constituent of CoA thiamine is not the coenzyme (co-carboxylase) of the enzyme carboxylase like in other organisms, for acetaldehyde has not been detected in propionibacteria (although traces were recently found), but it may function as a component of dehydrogenases in oxidative phosphorylation of a-keto acids. Riboflavin is a constituent of FAD and FMN. Propionibacteria can synthesize vitamins B2 and B in considerable amounts (see below), but the other three vitamins must be supplied. Some strains can grow in synthetic media without thiamine (Silverman and Workman, 1939 Delwiche, 1949), in some other strains thiamine can be replaced by / -aminobenzoic acid. 

Deoxy-D-ribose 5-phosphate has been obtained by the action of a nucleoside phosphorylase and a mutase on hypoxanthine , by enzymic condensation of triose phosphate and acetaldehyde and by enzymic phosphorylation of D-2-deoxyribose . Acid hydrolysis of deoxy-adenylic or deoxy-guanylic acid yields deoxyribose 5-phosphate . A chemical s)mthesis is available . 

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