The use of a monosaccharide linkage group in a heterologous solid-phase enzyme immunoassay for phenytoin

The preparation is described of monosaccharide-hapten derivatives containing a galactosyl linkage group which bears little structural resemblance to the straight-chain hydrocarbons commonly used for attaching haptens to proteins for use as immunogens. These derivatives are readily synthesised and are coupled to enzymes under mild conditions to produce bridge-heterologous enzyme immunoassays. The use of beta-galactosidase-monosaccharide-phenytoin derivatives in the development of sensitive phenytoin enzyme immunoassays is described and the assays are compared with hapten-heterologous, site-heterologous and homologous phenytoin enzyme immunoassays prepared using other phenytoin derivatives. This technique has application in the development of immunoassays for haptens which have only one functional group to which linkage groups can be attached for covalent coupling of the hapten to proteins.