6-phosphate acetylation

Jhis article discusses the present status of the mechanism of carbamyl phosphate (carbamyl-P) formation and illustrates that the reagents acetyl phosphate (acetyl-P) and carbamyl-P can replace each other with a number of well defined and/or highly purified enzymes. 

Considerable effort has been applied to studies of ester hydrolysis catalyzed by imidazoles (76MI40700, 80AHC(27)241). Certainly, 1-acetylimidazole can be made enzymically, probably by the sequence acetyl phosphate + coenzyme A acetylcoenzyme A+phosphate, acetyl-coenzyme A + imidazole l-acetylimidazole+coenzyme A. In addition, the imidazolyl group of histidine appears to be implicated in the mode of action of such hydrolytic enzymes as trypsin and chymotrypsin, thereby engendering further interest in the process of imidazole catalysis. The two pathways which have been found to be involved are general base catalysis and nucleophilic catalysis. In the former (Scheme 26) a basic imidazole molecule can activate a water molecule to attack the ester at the carbonyl carbon, this being followed by the usual sequence of steps as in simple hydroxide ion hydrolysis. At high imidazole concentrations the imidazole molecules may be involved directly. 

Considerable effort has been applied to studies of ester hydrolysis catalyzed by imidazoles (76MI40700, 80AHC(27)241). Certainly, 1-acetylimidazole can be made enzymically, probably by the sequence acetyl phosphate + coenzyme A acetylcoenzyme A + phosphate, acetyl-coenzyme A + imidazole 1-acetylimidazole-I-coenzyme A. In addition, the imidazolyl... 

Scheme 6 illustrates the use of these protecting groups in the phosphorylation of 2 -deoxynucleosides by Michelson and Todd. 5 -0-Trityl-thymidine (110) was phosphorylated with dibenzyl phosphorochloridate (44) to (111), which, after treatment with 80% acetic acid, afforded thymidine 3-(benzyl phosphate) (112). Catalytic hydrogenolysis of (112) gave thymidine 3 -phosphate. Acetylation of (110) yielded the 3 -acetate (114) which, on detritylation to (115), followed by phosphorylation, catalytic reduction, and deacetylation, gave thymidine 5 -phosphate (116), identical with the thymidylic acid obtained by enzymic hydrolysis of 2 -deoxyribonueleic acid. A rather similar sequence was applied to the preparation of the 2 -deoxycytidine analogs of (113) and (116). 

Acetyl adenylate Phosphoeijol pyruvate Creatine phosphate Acetyl phosphate Adenosine triphosphate (ATP) Glucose-i-phosphate Fructose-6-phosphate Fructose-1 -phosphate... 

Acacia Acetylated distarch adipate Acetylated distarch glycerol Acetylated distarch phosphate Acetylated hydrogenated cottonseed glyceride... 

Acacia Acetylated distarch adipate Acetylated distarch glycerol Acetylated distarch phosphate Acetylated oxidized starch Algin Alginic acid Aloe barbadensis extract Aloe extract Aluminum silicate Ammonium alginate /Ammonium carrageenan Ammonium furcelleran Ammonium pectinate Arabinogalactan... 

Another method by which acyl-SCoA derivatives may be formed is by a substitution reaction in which the phosphate group of acyl phosphates is replaced by CoASH. Thus a reaction between acetyl phosphate (acetyl-P) and CoASH leads to the formation of acetyl-SCoA (4, 16) [reaction (6)]. 

Additives used in final products Plasticizers 2-ethylhexyl diphenyl phosphate, acetyl tributyl citrate, acrylic resin (Aoronal 700 L), aliphatic polyurethane, butyl benzyl phthalate, camphor (plasticizer of celluloid), castor oil, dibutyl phthalate, dimethyl phthalate, dllsooctyl phthalate, epoxidized soybean oil, glyceryl triacetate, glyceryl tribenzoate, glyceryl tribenzoate, N-ethyl (o,p)-toluenesulfonamide, octyl diphenyl phosphate, sucrose acetate isobutyrate, tricresyl phosphate, triethylene glycol, urea resin Antistatics poly(3,4-ethylenedioxythiophene sulfonate), vanadium pentoxide Slip alumina, silica Amines (stabilizers of gunpowder) ... 

AcCoA, acetyl-CoA pta, phosphate acetyl-transferase ackA, acetate kinase ppc, PEP carboxykinase mdh, malate dehydrogenase fum, fumarase frd, fumarate reductase pyc, pyruvate carboxylase and pykF, pyruvate kinase. This figure was redrawn based on [36]. With permission 2009 Federation of European Microbiological Societies published by Blackwell Publishing Ltd. 

MAL, malate FUM, fumarate. ppc, PEP car-boxykinase pekA, PEP carboxykinase pykF, pyruvate kinase maeB, malic enzyme mdh, malate dehydrogenase fumC, fumarase frdABCD, fumarate reductase IdhA, lactate dehydrogenase pHB, pyruvate fbrmatelyase pta, phosphate acetyl-transferase ackA, acetate kinase adhE, alcohol dehydrogenase and MQ, menaquinone. 

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