Pepsin catalytic action

Fruton, J., 1976. The mechanism of die catalytic action of pepsin and related acid proteina.ses. Advances in Enzymology 44 1-36. 

We have approached this problem by studying the interactions between pepsin and ketones with structures based on that of pepstatin. Our strategy was to design ketones which would serve as pseudosubstrates, that is, be subject to the catalytic action of the enzyme, but only to the point of formation of a tetrahedral intermediate which, because of the increased stability of a C-C vs a C-N bond, would not break down to products. Such a stable tetrahedral intermediate would then, in principle, be amenable to study by the appropriate physical methods. appeared to be an ideal method since changes... 

Four reviews dealing with the mechanism of action of pepsin have been published in recent years (46, 73, 108, 117). Other recent publications deal with various aspects of this mechanism 118-120). In this section, therefore, the main emphasis will be placed on the significance of studies on hitherto unobserved pepsin- and penicillopepsin-catalyzed transpeptidation reactions, especially as they aflFect the mechanisms proposed by various authors. The question we are concerned with is the role of the two carboxyl groups which are involved in the catalytic action. We shall not further consider the role of other functional groups which have been discussed in the previous section. 

Fruton, J.S. (1976) The Mechanism of the Catalytic Action of Pepsin and Related Acid Proteinases, Adv. Enzymol. Relat. Areas Mol. Biol., 44, 1-36. 

Enzyme Any of various complex organic substances, as pepsin, originating from living cells and capable of producing certain chemical changes in organic substances by catalytic action, as in digestion. 

Porcine pepsin is known to have two types of activities in acidic solution the catalysis of peptide bond hydrolysis and the catalysis of transpeptidation (1). The presence of amino-enzyme intermediates in the catalytic action of pepsin has been proposed by Knowles (2-4) and Antonov (5). On the other hand. Silver... 

Active pepsin was crystallized by Northrop. It is a protein with a molecular weight of 34,500, whose isoelectric point is unusually low (below 1). A phosphoric acid residue in the molecule, although dispensable for the catalytic action, is responsible for the very low pi. Pepsin has optimal activity at the acidity of the gastric juice (for pH optimum see Table XI). 

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