The optimum pH at which the enzymes pepsin and trypsin of the human alimentary canal works are

The human digestive system utilizes specific enzymes that function optimally at different pH levels depending on their location in the alimentary canal. Pepsin is a protease secreted by gastric glands in the stomach [1]. It requires a highly acidic environment, created by hydrochloric acid, to convert from its inactive form (pepsinogen) into active pepsin [2]. Its optimum activity occurs at approximately pH 2.0 [1]. Conversely, trypsin is a pancreatic enzyme released into the small intestine to continue protein digestion [2]. Unlike the stomach, the small intestine maintains a slightly alkaline environment due to the neutralization of stomach acid by bile and pancreatic secretions. Trypsin works most efficiently in these alkaline conditions, with an optimum pH of approximately 7.9 to 8.0 [1]. Therefore, the respective optimum pH values for pepsin and trypsin are 2.0 and 7.9.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.3 > p. 85
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.3 > p. 86