Effect of Temperature on Activity of Digestive Enzymes in Silurus lanzhouensis

The protease,amylase and lipase activities in Silurus lanzhouensis under the condition of different temperature(15℃,20℃,25℃,30℃,37℃,42℃ and 47℃) were studied.The results showed that: with the increasing of temperature,the digestive enzymes' activities increased at first,then decreased.The optimum temperatures of the protease in all digestive tissues and organs were 42℃;those of amylase were 30℃ except stomach and hepatopancreas,which was 37℃; those of lipase were 25℃ except posterior intestine,which was 30℃.The optimum temperatures of these enzymes were higher than the temperature that the fish lived in,which showed the protein of enzymes' thermostability.Under respective optimum temperature,protease activity changed in the order from high to low as anterior intestine ≈middle intestineposterior intestinehepatopancreas≈stomach;amylase activity changed as anterior intestinemiddle intestinehepatopancreasstomachposterior intestine;lipase activity changed as middle intestineposterior intestineanterior intestine≈ hepatopancreasstomach,which showed that anterior intestine and middle intestine are the main positions in digesting protein,also anterior intestine and middle intestine are the main positions in digesting amylase and lipid respectively.The activity of protease is higher than that of amylase in the temperature from 25℃ to 37℃.The result also showed that the range of temperature for lipase to exert its activity was narrower than that of protease and amylase.