Tumor and placental histaminase, I. affinity chromatography purification and characterization of the placental enzyme.

Histaminase (diamine oxidase) is an enzyme produced at very high levels by the decidua of the placenta and is found to be associated with a number of human cancers. A procedure for the affinity chromatography purification of this enzyme is described. In this procedure, cadaverine-AH-sepharose was used to bind the enzyme in the placental extract. After extensive washing of the column with 2.5% Triton X-100 in 1 M NaCl, the enzyme was released from the column by 0.1 N chromotropic acid. This purification, essentially a one step procedure, provided 1800-fold purification, and yielded mg quantities of histaminase, homogeneous by SDS-gel electrophoresis and immunodiffusion tests. The procedure usually recovered more than 40% of the enzyme applied and the specific activity of the final enzyme preparation was around 5000 units/mg protein. SDS-gel electrophoresis of the enzyme in different concentrations of acrylamide indicated that the subunit molecular weight of histaminase was about 90,000. Isoelectric focusing of the enzyme in polyacrylamide gel revealed 5 major enzyme components. Results of amino acid analyses indicated that the enzyme had a low content of sulfur-containing amino acids and a relatively high content of dicarboxylic amino acids. The availability of this purification will be useful for the development of immunological methods for detections and quantitation of this enzyme in specimens from cancer patients.