[Enzyme immunoassay for arginine vasopressin (AVP). 1. Enzyme labelling of AVP and its application for AVP standard curve].

Enzyme immunoassay for arginine vasopressin (AVP) was developed in this study. Enzyme-labelling of AVP and then application of the enzyme-labelled AVP to make an AVP standard curve were done. Also, the anti-AVP antibody was obtained from the immunized rabbits. The enzyme (beta-D-galactosidase) was combined with AVP by using the N-hydroxysuccinimide ester of N-(4-carboxycyclohexylmethyl)-maleimide. The AVP-beta-D-galactosidase complex was examined for the competitive binding with AVP to the anti-AVP antibody. Then, the solid phase (polystylene bead) coupled with IgG fraction of anti-rabbit IgG serum (goat) was used to separate the antigen-antibody complex. The enzyme activity of this complex was measured to obtain an AVP standard curve. As a result, enzyme immunoassay for AVP described here was sufficiently sensitive and specific. Thus, this enzyme immunoassay could be applied for the determination of physiological levels of AVP in plasma. It is advantageous that the AVP-beta-D-galactosidase complex was stable for several years with respect to enzyme activity and immunological activity. The specific anti-AVP antibody with high titer was gained from the immunized rabbits using bovine thyroid globulin as a carrier protein.