Methods in Enzymology 1972-01-01

[54] amidination.

M J Hunter, M L Ludwig

Index: Meth. Enzymol. 25 , 585, (1972)

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Abstract

This chapter presents the class of compounds, RC(=NH)OX, that is referred to as imidoesters and where X is the ester R group. Specific compounds are called imidates, for example, methyl acetimidate. The amidination of proteins is reviewed. In reactions involving the complete amidination of a protein, however, the necessary presence of large excesses of imidoester is result in a large fraction of the imidoester being consumed by reaction with water. Since the hydrolysis may proceed by several, pH dependent, simultaneous pathways it is not possible to predict the resultant pH changes. In modification of proteins above pH 8 with methyl acetimidate and methyl benzimidate, acid must be added to maintain the pH. Removal of the products of reagent hydrolysis by dialysis and repetition of the reaction is an effective procedure for exhaustive amidination. One significant advantage of the amidination reaction is that it results in minimal nonspecific perturbations of protein structure. The chapter also discusses a few further illustrations of alterations in physical or biological properties following amidination of lysyl residues.