Galactosyl transferase assay. Application to experimental atherosclerosis.

To establish a repetitive measurement, aortic galactosyl transferase activity has been studied with a specific exogenous acceptor, collagen. Reactions were realized with an acellular biosynthesis mixture containing, collagen (3-4 mg/ml) an aliquot of enzymatic extract preparation (105000 g supernatant (2-3 mg/ml of proteins), UDP (14C) galactose (300 pM/ml). Galactose incorporation into collagen required Mn++ (2.5. 10-3M), incubation temperature of 37 degrees C and pH =7,75. Under such conditions a reproducible assay of aortic collagen galactosyl transferase was possible. After submitting rabbits to a chronic lathyric intoxication and/or to an hypercholesterolimic diet, galactosyl transferase activity was measured in rabbit aortic wall. Enzymatic activity was increased for rabbits under treatment, and the increase was directly proportional to the length of treatment (BAPN associated with cholesterolemic diet).