Development of enzyme immunoassay for chromomycin A3 and olivomycin using beta-D-galactosidase as a label.

An antibody specific for chromomycin A3 (CHM; byname, toyomycin) was produced in sufficiently high titer in rabbits by immunization with a CHM-bovine serum albumin conjugate, prepared using diazotized p-aminobenzoic acid as a coupling agent. CHM was also coupled with beta-D-galactosidase (EC 3.2.1.23) using diazotized m-aminobenzoic acid and was used as a tracer. With these reagents, a double-antibody enzyme immunoassay for CHM and for the CHM homologue olivomycin was developed which was highly sensitive and accurate enough to measure as little as 10 and 50 pg of each drug per assay tube, respectively. The enzyme immunoassay did not cross-react with mithramycin and drugs commonly used with CHM in combination chemotherapy for cancer treatment. Using this assay, drug levels were easily determined in blood and urine of rats following administration of CHM in a single dose of 2.0 mg/kg i.v. The sensitivity and specificity of the enzyme immunoassay for CHM and olivomycin should provide a valuable new tool for use in pharmacokinetic and toxicity studies of these drugs.