Hydrolysis kinetics amides, 295, Table

Table 2.5 summarizes the hydrolysis kinetic data for a number of aliphatic amides. 

The composition and concentration of polymers in the test solutions for hydrolysis are shown in Table 1. The concentration of the sodium acrylate and sodium AMPS copolymers with acrylamide were calculated to provide 0.025 molar solutions of amide units, to simplify the kinetics. 

A variety of N-O-chelated glycine amide and peptide complexes of the type [CoN4(GlyNR R2)]3+ have been prepared and their rates of base hydrolysis studied.169 The kinetics are consistent with Scheme 8. Attack of solvent hydroxide occurs at the carbonyl carbon of the chelated amide or peptide. Amide deprotonation gives an unreactive complex. Rate constants kOH are summarized in Table 16. Direct activation of the carbonyl group by cobalt(III) leads to rate accelerations of ca. 104-106-fold. More recent investigations160-161 have dealt with... 

Both alkaline proteases form an intermediate, the acyl-enzyme complex, on the reaction coordinate from the amino acid component to the dipeptide, which is formed by the triad Ser-(or Cys-)-His-Asp (or -Glu) (see Chapter 9, Section 9.5). The acyl-enzyme complex can be formed with the help of an activated amino acid component such as an amino acid ester. The complex can react either with water to the undesired hydrolysis product, the free amino acid, or with the amine of the nucleophile, such as an amino acid ester or amide, to the desired dipeptide. The particular advantage of enzyme-catalyzed peptide synthesis rests in the biocatalyst specificity with respect to particular amino acids in electrophile and nucleophile positions. Figure 7.26 illustrates the principle of kinetically and thermodynamically controlled peptide synthesis while Table 7.3 elucidates the specificity of some common proteases. 

The base hydrolysis of the carbonyl bonded amides and peptides display a first order dependence on the hydroxide ion concentration up to a pH of ca. 10, but then become independent of the hydroxide ion concentration due to the formation of the unreactive deprotonated amide (pK = 11 to 12). Some typical kinetic data for these reactions are summarised in Table 7.6. The p2-Co(trien) complexes have the configuration shown in (7.12). Similar studies have been carried out with complexes of the general type trans-[Co(dien)X(peptideOR)] (7.13). Typical kinetic results... 

Table 3 Kinetic Parameters for the Hydrolysis of Different ct-H-Amino Acid Amides by Purified L-Aminopeptidase from P. putida ATCC 12633...

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