James P. Albarella

A colorimetric immunoassay based on an enzyme inhibitor method

A competitive binding immunoassay was developed using an enzyme inhibitor for labeling the analyte. Thyroxine was labeled by covalent coupling of the alpha-amino group to the gamma-carboxyl of the glutamyl residue of methotrexate. This thyroxine-methotrexate conjugate was a potent inhibitor of dihydrofolate reductase. When antibody was bound to the thyroxine moiety, the inhibitor was inactivated. Thus, a competitive binding immunoassay for thyroxine was demonstrated based on colorimetric measurement of dihydrofolate reductase activity.

Use of high-performance liquid chromatography in the preparation of flavin adenine dinucleotide analyte conjugates

Abstract High-performance liquid chromatography (HPLC) was used for the study of the chemical synthesis of the flavin adenine dinucleotide analyte conjugates. A preparative HPLC method was also developed for the purification of the conjugates directly from the reaction mixture with minimum sample pretreatment. The preparations of flavin N6-(N-6-aminohexyl)adenine dinucleotide and flavin adenine dinucleotide theophylline conjugate are given as examples to illustrate the importance of this method.