Pepsin

Pepsin (Pepsinum) - enzyme gastric juice. Molecular weight of 35 000. The molecule of pepsin consists of 340 amino acid residues. Pepsin hydrolyzes proteins to peptides. Optimal effect when the pH of approximately 2.0. Predecessor pepsina - pepsinogen produced by cells of the mucous membrane of the stomach turns into pepsin in the presence of hydrochloric acidcontained in the gastric juice. Pepsin is the drug (Pepsinum siccum)is obtained by extraction from the mucous membrane of stomach swine, sheep and calves. Used in Hypo - and anatsidnyh gastritis, dyspepsia. Pepsin assign inside of 0,2-0,5 g per reception 2-3 times a day before meals or with food in the form of powder or 1-3% solution divorced hydrochloric acid. The release form: powder.
Cm. also Gastric juice, Enzymes.

In fundic gland stomach daily produced 1 g of pepsinogen, which of the stomach cavity under the action of hydrochloric acid is activated, turning into pepsin. Molecular weight of pepsinogen is 42 000, pepsin - 35 000. The optimum pH for pepsin is 1.5-2. A large part of the enzyme enters the stomach and plays an active role in the digestive process, but a number of pepsinogen enters the bloodstream and excreted by the kidneys.
Pepsin breaks down almost all the proteins, except for some protaminom. Hydrolyzed synthetic peptides, if both sides have severed relations are L-amino acids. In the rest of specificity in respect of amino acids insignificant, although there is a preference in respect of aromatic amino acids.

Pepsin is an enzyme gastric juice. Refers to a group of proteinases (see Protease); received in crystalline form. Mol. century 35 000, isoelectric point approx. pH = 1. In addition to the Isthmus, in the gastric juice (see) there are several related proteolytic enzymes (e.g. gestrichen).
The most pure drugs P. receive when chromatography columns with dietilaminometiltselljuloza. The molecule of pepsin is a single polypeptide chain of about 340 amino acid residues. Dephosphorylation P.'t destroy its enzymatic activity. Naibolee stable at pH 5-5,5, in a more acidic environment is self-digestion. P. hydrolyzes proteins to peptides; among the products of hydrolysis meet and amino acids. Undergo hydrolysis of peptide bonds formed by different amino acid residues. P. able to catalyze the reaction of transpeptidase (transfer of amino acid residues from one peptide on the other). Optimum action P. is about pH=2; pH=5 P. causes stvorazhivanii milk with a pH above 6 is rapidly inactivated.
Inactive precursor P. - pepsinogen produced by cells of the mucous membrane of the fundus of the stomach turns into Petrograd in the presence of hydrochloric acid contained in the gastric juice. The activation process flows autocatalytic with maximum speed at pH=2. From the N-terminal portion of the molecule pepsinoguena cleaved several peptides with General mol. century OK. 8000. Selected inhibitor P. - peptide with mol. century OK. 3000, which is formed from pepsinoguena during its transformation in Petrograd During activation formed an intermediate connection with P. polypeptide inhibitor that is easy to dissociate at low pH values and inhibitor digested P. At pH>5 dissociation minor and inhibition of pepsin is almost stoichiometric ratios.
Pepsin (the drug). Pepsin (Pepsinum siccum) is obtained by extraction of mucous membranes stomach swine, sheep or a calf. Applied as a means of substitution therapy in acute and chronic diseases of digestive tract, accompanied by the impoverishment of gastric juice endogenous pepsin. For medical applications P. dilute to official standard (1:100) with milk sugar. Inside appoint adults : 0,2-0,5 g per reception 2-3 times a day before meals or with food in the form of powder or 1-3% solution divorced hydrochloric acid; children of 0.05 up to 0.5 g of 0.5-1% solution divorced hydrochloric acid. The release form: powder.