On the size of the active site in proteases. I. Papain.

Acetylornithinase of Escherichia coli: partial purification and some properties.

The preparation and properties of two new chromogenic substrates of trypsin.

https://www.farm.ucl.ac.be/Full-texts-FARM/Danhier-2010-2.pdf

To exploit the tumor microenvironment: Passive and active tumor targeting of nanocarriers for anti-cancer drug delivery

The spectrophotometric procedure proposed by Schwert and Takenaka for the assay of chymotrypsin and trypsin has been modified and extended to include the application to N-benzoyl-L-tyrosine ethyl e...

A modified spectrophotometric determination of chymotrypsin, trypsin, and thrombin.

Oligopeptide substrates of porcine pepsin (E) of the type A-Phe-Phe-B (S) that are cleaved solely at the Phe-Phe bond under the conditions of these studies, and bearing an amino-terminal fluorescent probe group (mansyl or dansyl), have been used for stopped-flow measurements of the rate of formation of the A-Phe product. These experiments were conducted under conditions of [E] greater than [S], and the kinetic data were compared with those obtained under conditions of [S] greater than [E] for the formation of the Phe-B product (the same in all cases). The results for substrates with A = mansyl-Gly, mansyl-Gly-Gly, and dansyl-Gly-Gly support the conclusion that the rate-limiting step in the over-all catalytic process is associated with the scission of the Phe-Phe bond in the first detectables ES complex. Although the rate of this step varies widely with the nature of the A portion of A-Phe-Phe-B, the magnitude of the dissociation constant of ES is relatively invariant. This supports the view that, in the cleavage of oligopeptide substrates by pepsin, secondary enzyme--substrate interactions may cause conformational changes at the catalytic site, and that a portion of the total binding energy may be used for the attainment of the transition state in the bond-breaking step. With substrates that are hydrolyzed extremely rapidly (A = dansyl-Gly-Ala, dansyl-Ala-Ala), the rate of formation of the A-Phe product appears to be faster than the steady-state rate, suggesting that an additional step has become kinetically significant in the over-all process. This step may be associated with the return of the conformation of the active site to its original state.

Joseph S. Fruton

Papers

Kinetics of action of pepsin on fluorescent peptide substrates

Some properties of beef spleen phosphoamidase.

The inhibition of pepsin action.

Proteinase-catalyzed transamidation and its efficiency.

The side-chain specificity of pepsin.