Radioimmunoassay of oxidized calmodulin in chloramine-T treated tissue samples.

We found that a short incubation of calmodulin with chloramine-T alters its antigenic structure. Antisera elicited by performic acid oxidized calmodulin only bind with chloramine-T treated calmodulin. Based on this finding we have developed an assay for the determination of calmodulin in small tissue samples. Tissue homogenates are incubated with 10 mmol/l chloramine-T before calmodulin quantification. Immune complexes are isolated by sodium sulphate precipitation. [125I]calmodulin is used as tracer.