Description_x000D_ General description_x000D_ Papain is a thermostable enzyme and becomes inactive at 55°C. It has two domains and the catalytic region is present at the domain interface. The cysteine 25 in the active site performs the proteolysis by nucleophilic attack on the carbonyl carbon of a peptides. Papain has wide industrial applications in food and pharmaceutical industry._x000D_ Application_x000D_ Papain is used in dissecting solutions. It is used to produce Fab fragments of antibodies . It is used for cell dissociation since it has been shown to be more effective and less damaging with certain tissues. Papain has been used to isolate morphologically intact cortical neurons from postnatal rats. Limited papain digestion is used for structural studies of enzymes and other proteins. In addition, papain is used in red cell serology to modify the red cell surface to enhance or destroy the reactivity of many red cell antigens. Papain is useful for platelet serology studies. Papain has also been used in the enzymatic synthesis of amino acids, peptides, and other molecules. Product P5306 is provided as a lyophilized powder that is aseptically filled. It has been used to digest mouse retinas to study the RAGE axis in nonproliferative diabetic retinopathy (NPDR)._x000D_ The product from Sigma has been used in the digestion of extracellular matrix (ECM). It has also been used with other proteolytic enzymes for in situ protein degradation to produce crystals suitable for structure determination._x000D_ Used to produce Fab fragments of antibodies. Also used for cell dissociation since it has been shown to be more effective and less damaging with certain tissues._x000D_ Biochem/physiol Actions_x000D_ Papain papaya latex has antifungal activity against C. albicans. Papain consists of a single polypeptide chain with three disulfide bridges and a sulfhydryl group necessary for activity of the enzyme._x000D_ A cysteine protease that cleaves peptide bonds of basic amino acids, leucine, or glycine._x000D_ pH optimum 6.0-7.0_x000D_ Also hydrolyzes esters and amides._x000D_ Unit Definition_x000D_ One unit will hydrolyze 1.0 μmole of BAEE per minute at pH 6.2 at 25 deg C._x000D_ Preparation Note_x000D_ Prepared from P 4762_x000D_ Other Notes_x000D_ View more information on papain at www.sigma-aldrich.com/enzymeexplorer.