Practical Protein Chemistry - A. Darbre 1989

Enzymatic fragmentation of the polypeptide chain
Proteases with low specificity
Elastase

Elastase is a Serine protease homologous to Chymotrypsin and Trypsin. A detailed Description of the enzyme's properties is given in [40]. Elastase is commercially available from several manufacturers.

3.6.5.1. Specificity and Hydrolysis conditions.

Specificity. Elastase is characterized by a broad specificity. The enzyme predominantly hydrolyzes C-terminal peptide bonds of amino acid residues with small hydrophobic side chains, such as Alanine [40]. Studies on elastase specificity have revealed the hydrolysis of peptide bonds adjacent to neutral amino acid residues [72]. Treatment of oxidized Insulin chains showed Cleavage at Ser, Ala, Gly, Val, and Leu residues.

Reaction conditions. Hydrolysis is carried out under conditions similar to those for trypsin and chymotrypsin, i.e., in 100 mM NH₄HCO₃ at 37 °C for 1–4 h at an Enzyme-to-substrate ratio of 1 : 50.

3.6.6. α-Protease from Crotalus atrox

α-Protease is isolated from the venom of Crotalus atrox. The properties of the enzyme are described in [77, 125]. The enzyme hydrolyzes N-terminal peptide bonds of hydrophobic amino acid residues [77, 66] and thus, in terms of specificity, is analogous to Thermolysin. α-Protease exhibits maximum activity at pH 7.5–8.0 and is sometimes used in determining the Introduction/19.html">Primary Structure of Proteins [107]. However, further research is required to fully unlock the potential of this enzyme. The enzyme is available commercially from Pierce.