Production of a high affinity antibody specific to the calcium-free-form of calmodulin, using N-acetyl-muramyl-L-alanyl-D-isoglutamine-calmodulin conjugate.

Covalent coupling of N-acetyl-muramyl-L-alanyl-D--isoglutamine (MDP) to calmodulin was used in order to enhance its immunogenicity. Rabbit antibodies against calmodulin were obtained, interacting with the calcium--free-form of calmodulin. The radioimmunoassay was developed using the whole sera (titre 1:20,000) having a sensitivity of 20 pg per tube (50% displacement 500 pg/assay tube). The radioimmunoassay shows the same concentrations of calmodulin in rat brain homogenate (4.9 +/- 0.86 micrograms/mg protein), bovine neurosecretosomes (0.77 +/- 0.10 microgram/mg protein), and bovine neurohypophysial secretory vesicles (0.05 +/- 0.01 microgram/mg protein) as the phosphodiesterase activation method.