Prithipal Singh

A method for controlled coupling of amino compounds to enzymes: A homogeneous enzyme immunoassay for gentamicin

Abstract A new method for coupling of amino compounds to enzymes is described. An aminoglycoside, gentamicin, is functionalized with a nucleophilic sulfhydryl group on its deoxystreptamine ring and an enzyme, glucose 6-phosphate dehydrogenase (G6PDH), is modified with electrophilic bromoacetylglycyl groups. Upon modification, the G6PDH loses about 70% of its enzyme activity. Coupling of the modified G6PDH with the sulfhydryl-substituted gentamicin affords, without further loss in activity, the drug-enzyme conjugate. Gentamicin antibodies inhibit up to 76% of the enzyme activity of the conjugate. The conjugate is demonstrated to be useful for a sensitive, homogeneous enzyme immunoassay for gentamicin in human serum.