Thermolysin from Geobacillus stearothermophilus

Thermolysin is a protease that has specificity different from other proteases available for sequence investigations.

A thermostable (thermophilic) extracellular metalloendopeptidase containing four calcium ions. Cofactors are zinc and calcium. Hydrolyzes protein bonds on the N-terminal side of hydrophobic amino acid residues. The pH optimum is 8.0 and the optimal temperature for activity is 70 °C. Considerably stable from pH 5 to 9.5. Thermolysin has a low cleavage specificity, therefore, it produces a number of short fragments that are suitable for sequencing. Preferential cleavage: X-cleavage-Y-Z where X=any amino acid; Y=Leu, Phe, Ile, Val, Met, Ala and Z is any amino acid other than Pro. Cleavage N-terminal to Leu is preferred over cleavage of N-terminal to Phe which is preferred over the others. Often used to do limited proteolysis for peptide mapping and studies of protein structure and conformational changes.

Thermolysin has been shown to have a prosequeence that acts as an intramolecular chaperone in vivo. It has also been used in a study to investigate the effects of sodium chloride on thermal stability and catalytic activity.

Thermolysin is also commonly used for the commercial synthesis of N-(benzyloxycarbonyl)-L-aspartyl-L-phenylalanine methyl ester, the precursor for the artificial sweetener aspartame.

lyophilized powder containing calcium and sodium acetate buffer salts

The pH optimum is 8.0 and the optimal temperature for activity is 70 °C. Considerably stable from pH 5 to 9.5. Thermolysin has a low cleavage specificity, therefore, it produces a number of short fragments that are suitable for sequencing. Preferential cleavage: X-cleavage-Y-Z where X=any amino acid; Y=Leu, Phe, Ile, Val, Met, Ala and Z is any amino acid other than Pro. Cleavage N-terminal to Leu is preferred over cleavage of N-terminal to Phe which is preferred over the others.

Contains many extraneous enzymes.

One unit will hydrolyze casein to produce color equivalent to 1.0 μmole (181 μg) of tyrosine per min at pH 7.5 at 37 °C (color by Folin-Ciocalteu reagent).