Influence of neuraminidase treatment on the electrophoretic behaviour of angiotensin converting enzyme from human tissues.

Angiotensin converting enzyme (dipeptidyl carboxypeptidase, kininase II; EC 3.4.15.1), is a membrane bound glycoprotein, playing an important role in the renin-aldosterone system. The enzyme contains a carbohydrate moiety, consisting of fucose, mannose, galactose, N-acetylglucosamine and N-acetylneuraminic acid. Treatment with neuraminidase (EC 3.2.1.18) removes sialic acid from the molecule. The influence of this treatment on the electrophoretic mobility of the enzyme was studied in 29 human tissues and body fluids. Results obtained showed differences in the sialic acid content of the enzyme in the tissues examined.