Rapid gentamicin assay by enzymatic adenylylation.

A method is described for the assay of gentamicin using the enzyme gentamicin adenylyltransferase derived from an R-factor-carrying strain of Escherichia coli. The reaction involves adenylylation of the gentamicin with ((14)C)-ATP to form a radioactively labelled product. The technique is compared with the plate diffusion and the urease methods. The adenylylation technique gives results comparable to the plate diffusion assay and is more accurate than the urease method.