Acetylation s. a. Acylation

C-Acetyl... s. Methyl ketones Acetylation s. a. Acylation N-Acetylation, selective, with ketene 24,326... 

Selected entries from Methods in Enzymology [vol, page(s)] Assay, 1, 611 3, 935-938 63, 33 separation by HPLC, 72, 45 extraction from tissues, 13, 439 formation of, 1, 486, 518, 585 5, 466 free energy of hydrolysis, 1, 694 substrate for the following enzymes [acetyl-coenzyme A acyl carrier protein transacylase, 14, 50 acetyl-coenzyme A carboxylase, 14, 3, 9 acetyl-coenzyme A synthetase, 13, 375 N-acetyltransferase, 17B, 805 aminoacetone... 

Two disadvantages are associated with the use of S-acetyl or 5-benzoyl derivatives in peptide syntheses (a) base-catalyzed hydrolysis of 5-acetyl- and 5-benzoylcys-teine occurs with /S-elimination to give olefinic side products, CH2=C-(NHPG)CO—(b) the yields of peptides formed by coupling an unprotected amino group in an 5-acylcysteine are low because of prior S-N acyl migration. ... 

FIGURE 24.24 The oxidation pathway for polyunsaturated fatty adds, illustrated for linoleic add. Three cycles of /3-oxidation on linoleoyl-CoA yield the cis-A, d.s-A intermediate, which is converted to a tran.s-A, cis-A intermediate. An additional round of /S-oxi-dation gives d.s-A enoyl-CoA, which is oxidized to the trans-A, d.s-A species by acyl-CoA dehydrogenase. The subsequent action of 2,4-dienoyl-CoA reductase yields the trans-A product, which is converted by enoyl-CoA isomerase to the tran.s-A form. Normal /S-oxida-tion then produces five molecules of acetyl-CoA. 

Consideration of rotatory powers of l,l-bis(acylamido)-l-deoxy-alditols showed79 certain correlations between optical rotation (d line of sodium) and configuration that can be summarized as follows. (a) When the acyl group is aliphatic (for example, acetyl or propionyl), the alditol will be dextrorotatory in water if the configuration of C-2 is S. (The rule does not apply to peracetylated derivatives.) (b) When the two substituents on C-l are benzamido and the configuration at C-2 is S, a solution of the alditol in pyridine will be levorotatory. Peracetylation does not alter applicability of this rule, (c) The abso-... 

Sano, T. Ohashi, K. Oriyama, T. Remarkably fast acylation of alcohols with PhCOCl promoted by TMEDA. Synthesis 1999, 1141-1144. Carrigan, M. D. Freiberg, D. A. Smith, R. C. Zerth, H. M. Mohan, R. S. A simple and practical method for large-scale acetylation of alcohols and diols using Bi(OTf)3. Synthesis 2001, 2091-2094. 

Step 1 of Figure 27.7 Claisen Condensation The first step in mevalonate biosynthesis is a Claisen condensation (Section 23.7) to yield acetoacet)-) CoA, a reaction catalyzed by acetoacetyl-CoA acetyltranslerase. An acetyl group is first bound to the enzyme by a nucleophilic acyl substitution reaction with a c> s-teine —SH group. Formation of an etiolate ion from a second molecule of acetyl Co.A, followed by Claisen condensation, then yields the product. 

The mechanism of the OH-induced oxidation of N,S-diacetyl-L-cys-teine ethyl ester (SNACET) was investigated in aqueous solution using pulse radiolysis and steady-state y-radiolysis. The adjacent electron-withdrawing acetyl group destabilizes hydroxysulfiiranyl radical because of a very fast fragmentation 7.9 x 10 s ) into acyl rad-... 

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