Chymotrypsin heat treatment

When proteinoids were heated in buffer at pH 6.2 or 6.8, loss of catalytic activity was observed. The extent of loss ranged from 95 to 11% (Table II). Those proteinoids that initially showed higher levels of activity relative to histidine were the most affected by the heat treatment. After heating, the level of activity was comparable to that of the equivalent amount of histidine, or to that of mineral acid hydrolysates of the polymer. Under similar conditions, a-chymotrypsin was 97% inactivated. The fact that the control tests on L-histidine or A -carbo-benzoxy-L-histidine showed no effect is consistent with the inference that inactivation is due to disruption of a macromolecular conformation. Copolymers prepared from only aspartic acid and histidine were also active on NPA and were inactivated by the heat treatment. The percentages of inactivation ranged from 62 to 19. Polymers prepared and processed under aseptic conditions were both catalytically active and subject to inactivation by heat. These experiments were performed as routine verification that the respective phenomena do not result from the presence, and subsequent denaturation, of contaminating microbial enzymes. 

More than 97% of the available soybean meal is used for feed where extensive heat treatment is necessary to maximize feed conversion efficiency by livestock. Toasting inactivates protease inhibitors (especially trypsin and chymotrypsin inhibitors) and the enzyme urease, and improves protein digestibility. None of these objectives can be obtained without protein being denatured and loss in water solubility however, depending on the method used, meals with great differences in protein solubilities or dispersibilities can be produced. The optimum amount of heat treatment in toasting soybean meal is still debated among animal nutritionists. 

When purely chemical cross-linking reagent disuccinimidyl suberate was used, a different conjugate of 60 kDa was found. As prior treatment of the synaptosome with proteinase K, trypsin, subtilisin, a-chymotrypsin, elastase or heat destroyed this conjugation... 

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