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.

On the proteolytic enzymes of animal tissues: i. beef spleen

The rates of the thermolysin-catalyzed synthesis of peptides have been determined by means of HPLC. In the condensation of various N-substituted amino acids and peptides with L-leucinanilide, the enzyme exhibits preference for a hydrophobic L-amino acid as the donor of the carbonyl group of the newly formed bond. The presence of another hydrophobic amino acid residue adjacent to the carbonyl-group donor markedly enhances the rate of synthesis. In general, the effect of structural changes in both the carboxyl and amine components of the condensation reaction is in accord with the available data on the primary and secondary specificities of the thermolysin-catalyzed hydrolysis of oligopeptide substrates. A kinetic study of the condensation of benzyloxycarbonyl-L-phenylalanine with various amine components has given data on the apparent kcat and Km values for the entry of the acidic component into the condensation reaction. The results are consistent with the behavior of rapid-equilibrium random bi-reactant systems leading to ternary enzyme-substrate complexes, with a synergistic effect in the binding of the two reactants at the active site. Because the changes in the apparent kcat for the entry of the same acidic component into reaction with different amine components are greater than those in the apparent Km, it is suggested that this synergism is largely expressed at the level of the transition-state complex.

https://www.pnas.org/content/pnas/80/11/3241.full.pdf

Thermolysin-catalyzed peptide bond synthesis.

New Synthetic Substrates for Pepsin

Transamidation reactions catalyzed by cathepsins.

Of the many problems which have excited the curiosity of the biochemist, there are few more challenging than that presented by the mechanism of the synthesis of proteins in living cells. The biochemical journals of the past two decades are replete with discussions of the probable reaction paths followed during the biosyhthesis of proteins. In reviewing the salient literature concerning this question, it seems hest to start with the generally accepted view that proteins consist largely of amino acid residues that are linked to each other by means of peptide bonds. This theory is based on the experimental finding that when proteins are hydrolyzed by proteolytic enzymes or by acids or bases, there are formed amino acids and amino and carboxyl groups are liberated. It is natural, therefore, that the question has been asked whether the biosynthesis of a protein molecule involves a reversion of the hydrolytic action of the proteolytic enzymes. In other words, does protein synthesis begin with the condensation of a number of amino acids to form peptide bonds? The idea that the hydrolytic action of proteolytic enzymes might be reversed under certain experimental conditions is not a new one. Numerous investigators in the late nineteenth and early twentieth century observed that when proteolytic enzymes were added to concentrated solutions of the products of proteolysis, precipitates were frequently observed.’ Later workers noted a decrease in amino nitrogen in the reaction inixture.* These results were taken to indicate that protein synthesis had occurred, although the evidence presented for the protein nature of the precipitates was unconvincing. The further study of this problem was energetically pursued by Wasteneys and Borsook in the 1920’s. These investigators showed that when pepsin is allowed to act on egg albumin a t pH 1.6 and the solution of the products of peptic hydrolysis is adjusted to p H 4 and concentrated, addition of pepsin results in the formation of a precipitate, designated p l a ~ t e i n . ~ This product was described as a protein largely on the basis of its digestibility by pepsin and its precipitation by trichloracetic acid. There

Joseph S. Fruton

Papers

On the proteolytic enzymes of animal tissues: i. beef spleen

Thermolysin-catalyzed peptide bond synthesis.

New Synthetic Substrates for Pepsin

Transamidation reactions catalyzed by cathepsins.

The significance of coupled reactions for the enzymatic hydrolysis and synthesis of proteins