Studies of pig kidney diamine oxidase.

Preparations of pig kidney histaminase were analyzed for total compositions, N-terminal residues, patterns of tryptic peptides and for subunits under dissociating conditions. The crystalline enzyme is pure by several criteria but not completely homogeneous. It is rich in acidic or amidated residues and has a low content of cysteine/halfcystine. Preparation analyzed consistently contained a few percent of carbohydrate. Subunits are concluded to be identical or highly similar with a molecular weight of about 90 000, which is consistent with other analyses.