Phenylacetyl glycine

When H2O deacetylates the acyl-enzyme, phenylacetic acid is formed. When nucleophiles other than H2O deacylate the acyl-enzyme, a new condensation product, in this case phenylacetyl-O-R or phenylacetyl-NH-R is formed. By definition the hydrolysis of these condensation products can be catalyzed by the same enzyme that catalyzes their formation in equation 10.1. Thus, when the acyl-enzyme is formed from phenylacetyl-glycine or phenylacetyl-O-Me, this gives rise to an alternative process to produce Penicillin G, in addition to the thermodynamically controlled (= equilibrium controlled) condensation of phenylacetic acid and 6-aminopenicillanic acid (6-APA). This reaction that involves an activated side chain is a kinetically controlled (= rate controlled) process where the hydrolase acts as a transferase (Kasche, 1986 1989). 

A/-Phenylacetyl)glycine Phenaceturic acid C10H11NO3 600-98-1 193.199 11 (EtOH) 143 ... 

Wheal and flare reactions in penicillin-sensitized patients can also be elicited by protein conjugates of phenylacetyl glycine and dimethoxybenzyl glycine (SfflBATA et al. 1968). Using conjugates prepared with various penicillins, the side chain specificity of human skin-sensitizing antibodies has also been evaluated by several groups (Parker and Thiel 1963 Van Dellen et al. 1971). Exclusive or predominant side chain specificity of hypersensitivity may be responsible for the tolerance toward other penicillins of some patients who have been sensitized by penicillin G (Luton 1964). 

Glycine A -acyltransferase [EC 2.3.1.13] catalyzes the reaction of an acyl-CoA derivative with glycine to produce coenzyme A and an A-acylglycine. The acyl-CoA derivative can be one of a number of aliphatic and aromatic acids. However, neither phenylacetyl-CoA nor indole-3-acetyl-CoA can act as substrates. 

Two acyl-CoA amino acid A-acyltransferases have been purified from liver mitochondria of cattle, Rhesus monkeys, and humans. One is a benzoyltransferase CoA that utilizes benzyl-CoA, isovaleryl-CoA, and tiglyl-CoA, but not phenylacetyl CoA, malonyl-CoA, or indolacetyl-CoA. The other is a phenylacetyl transferase that utilizes phenylacetyl-CoA and indolacetyl-CoA but is inactive toward benzoyl-CoA. Neither is specific for glycine, as had been supposed from studies using less defined systems both also utilize asparagine and glutamine, although at lesser rates than glycine. 

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