Pepsin is an acid protease, contains a proteolytic enzyme. It contains the "cathepsin" component which has milk curdling activity. It has a broad range of substrate activity and demonstrates an esterase acitivity. It generally attacks peptide bonds.

• It is a peptidase used to digest proteins and is commonly used in the preparation of Fab fragments from antibodies. It has been used to hydrolyse dry cervical samples in mice.

Freely soluble in water, dissolves readily in 0,01 M HCl (0,5 mg/ml - clear, colourless solution)
Practically insoluble in alcohol, chloroform or ether
Extinction coefficient (E1%): E1%280=14,7
Enzyme Commission Number: E.C.3.4.23.1

Unit definition: One unit will produce a delta A280 of 0,001 per minute at pH 2,0 and 37 °C, measured as TCA-soluble products using hemoglobin as substrate.