Phosphate acetyl- AcP

An interesting point concerns the reversibility of all of the reaction steps shown in Scheme 12.6. This implies that under certain circumstances, the system might change its behaviour from an ATPase mimic to ATP synthase-type behaviour. This has been achieved through the use of a phosphorylating cofactor, acetyl phosphate (AcP, MeC02P032-). ar,d a divalent metal cation as a promoter (Mg2+ or Ca2+). Under... 

Figure 3 Chemical structures of dihydroxyacetone phosphate (DHAP ), glycerol 1-phosphate (GIP ), acetyl phosphate (AcP ), and acetonylphosphonate (AnP ).

A change in size of the potential 7-membered chelate ring (eq. 5) to a 6-membered one, demonstrates the importance of the steric orientation for weak interactions. Acetyl phosphate (AcP ) and acetonylphosphonate (AnP ) may form with metal ions 6-membered chelates as is show in equilibrium (6), where X = O (AcP l or CH2 (AnP l ... 

In practice, for most synthetic applications, either acetyl phosphate/acetate kinase or phosphoenolpyruvate/pyruvate kinase are used to regenerate ATP. Because of the ease of preparing AcP, AcP/AcK is the most economical method for large-scale work. Its application is, however, limited to fast phosphorylation reactions where the hydrolysis of AcP is not important. The PEP/pyruvate kinase system is used in instances where the requirement for a strong, stable phosphorylating reagent outweighs the relative inconvenience of preparation of PEP. 

Methoxycarbonyl phosphate/acetate kinase. Methoxycarbonyl phosphate (MCP 3) was designed to replace AcP as phosphoryl donor1181. It is comparable to PEP in its high phosphorylating strength (see Table 13-2), but resembles acetyl phosphate in its ease of synthesis. Aqueous solutions of MCP are prepared from aqueous phosphate and methyl chloroformate and used in ATP regeneration without purification. The reaction product after phosphoryl transfer is methyl carbonate, which hydrolyses rapidly to form C02 and MeOH. Product isolation is simple and bicarbonate inhibition can be avoided by purging the reaction mixture. 

AcK acetate kinase AcP acetyl phosphate AdK adenylate kinase AP A p ,pn-di(adenosine 5 -) n-phosphate ARS aminoacyl tRNA synthetase ATP, ADP, AMP adenosine 5 -tri-, di-, monophosphate ATP-u-S (Sp)-adenosine 5 -0-(l-thiotriphos-phate), ATP-y-S adenosine 5 -0-(3-thiotriphosphate) CK carbamyl kinase CP carbamyl phosphate CrK creatine kinase CTP, CDP, CMP cytidine 5 -tri-, di-, monophosphate dATP, dAMP deoxyadenosine 5 -tri-, monophosphate DNA deoxyribonucleic acid AG change in free energy GK glycerol kinase GTP, GDP, GMP guanosine 5 -tri-, di-, monophosphate HK hexokinase IUB International Union of Biochemistry MCP methoxycarbonyl phosphate NTP, NDP, NMP nucleoside 5 -tri-, di-, monophosphate PC phosphocreatine PEP phosphoenol pyruvate P orthophosphate PK pyruvate kinase P polyphosphate PnK poly-... 

Key AcK, acetate kinase AdK, adenylate kinase NAD-PP, NAD pyrophosphorylase PPase, pyrophosphorylase NADK, NAD kinase r-5-P, ribose-5-phosphate rA-5-P, ribosylamine-5-phosphate NMN, nicotinamide mononucleotide AcP, acetyl phosphate FPi, pyrophosphate and NDC, N J(2,4-dinitrophenyl)-3-carbamoylpyridinium chloride. 

Table 19.7. Infrared Absorption Bands", in cm of Acetyl Phosphate (as the Dianion, AcP ") and Carbamyl Phosphate" (as the Dianion, CAP )inthe1200-1800 cm Region in D O Solution (Oestreich and Jones, 1967)...

M acetyl phosphate lithium potassiirm salt (AcP) (Sigma-Aldrich), adjusted to pH 7.0 with KOH. 

The results reveal that baker s yeast is a potent source for precursors of 2-acetyl-l-pyrroline. It appears likely that the flavor compound is formed in the yeast cells from proline and dihydroxyacetone phosphate via 1-pyrroline and pyruvaldehyde. This is corroborated by the results of c-labeling experiments which showed that the acetyl group in the Acp stems from a sugar degradation product and that the pyrroline ring was derived from proline. 

Abbreviations FASN, fatty acid synthase ACC, acetyl-CoA-carboxylase ACL, ATP-citrate lyase NADPH, nicotinamide adenine dinucleotide phosphate MAT, malonyl acetyl transferases KS, ketoacyl synthase KR, p-ketoacyl reductase DH, p-hydroxyacyl dehydratase ER, enoyl reductase TE, thioesterase ACP, acyl carrier protein VLCFA, very long chain fatty acids ELOVL, elongation of very long chain fatty acids SCDl, stearoyl-CoA desaturase-1 AMPK, AMP-activated kinase ME, malic enzyme FASKOL, liver-specific deletion of FAS PPARa, Peroxisome Proliferator-Activating Receptor alpha HMG-CoA, 3-hydroxy-3-methyl-glutaryl-CoA SREBP, sterol response element binding protein SIP, site-one protease S2P, site-two... 

Fig. 10. Coordinate regulation of fatty acid and phospholipid metabolism. The pleiotropic regulator ppGpp regulates transfer of fatty acids to the membrane via inhibition of the PlsB acyltransferase step, coordinating phospholipid synthesis with macromolecular synttesis. PlsB inhibition leads to the accumulation of long-chain acyl-ACPs that feedback inhibit their own synthesis at the point of initiation (inhibition of acetyl-CoA carboxylase and FabH) and elongation, by inhibition of Fabl. LPA, lysophosphatidic acid G3P, glycerol-3-phosphate.

Amide bonds are found in many proteins. One is the acyl carrier protein of Escherichia coli (see 90), which contains the peptide backbone, and a 4 -phosphopantetheine unit (in violet in the illustration) is attached to a serine residue. Note the amine bonds in the pantothenic acid unit and also the 0-P=0 unit, which is a phosphate ester (an ester of phosphoric acid). An acyl carrier protein is involved in fatty acid synthesis, linking acetyl and malonyl groups from acetyl coenzyme A and malonyl coenzyme A to form P-keto acid acyl carrier protein (abbreviated as ACP). The widely utilized acetyl CoA is an ester (91) attached to coenzyme A. Acetyl CoA is a key intermediate in aerobic intermediary metabolism of carbohydrates, lipids, and some amino acids. 

XYL-5P xylulose 5-phosphate S7P sedo-heptulose 7-phosphate E-4P erythrose 4-phosphate COj carbon dioxide IPP isopentenyl pyrophosphate DMAPP dimethylallyl pyrophosphate AcP acetyl-P KDPG 2-keto-... 

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