Influence of Raw and Heated Soybean Meal and of Soybean Trypsin Inhibitors on the Activity of Certain Protein Catabolism Enzymes in Kidneys and Livers of Chicks and Rats

Abstract

Enzymatic activities involved in protein metabolism — liver xanthine dehydrogenase, liver xanthine oxidase (EC 1.2.3.2), liver aspartate aminotransferase (EC 2.6.1.2), liver and kidney arginase (EC 3.5.3.1) - were studied in chicks and rats fed diets containing the following soybean meals as protein sources: 1) heated soybean meal (HSBM); 2) raw soybean meal (RSBM); 3) HSBM + RSBM (2:1); and 4) HSBM supplemented with soybean trypsin inhibitors. RSBM decreased significantly the xanthine dehydrogenase, xanthine oxidase and arginase activity as compared with HSBM, whereas aspartate aminotransferase and alanine aminotransferase were affected slightly. The HSBM + RSBM or HSBM + soybean trypsin inhibitors did not show any clear influence on enzymatic activities. Diets with 25% protein gave higher enzymatic activity than those of 15% and methionine supplementation had no significant effect. Good correlation was found between the means of xanthine dehydrogenase and arginase activities in chicks and between the means of these activities and growth rate of each group.