Elastase

In molecular biology, elastase is an enzyme from the class of proteases (peptidases) that break down proteins.

Eight human genes exist for elastase:

Some bacteria (including Pseudomonas aeruginosa) also produce elastase. In bacteria, elastase is considered a virulence factor.

Elastase breaks down elastin, an elastic fibre that, together with collagen, determines the mechanical properties of connective tissue. The neutrophil form breaks down the Outer membrane protein A (OmpA) of E. coli and other Gram-negative bacteria. Elastase also has the important immunological role of breaking down Shigella virulence factors. This is accomplished through the cleavage of peptide bonds in the target proteins. The specific peptide bonds cleaved are those on the carboxyl side of small, hydrophobic amino acids such as glycine, alanine, and valine. For more on how this is accomplished, see serine protease.

Elastase is inhibited by the acute-phase protein α₁-antitrypsin (A1AT), which binds almost irreversibly to the active site of elastase and trypsin. A1AT is normally secreted by the liver cells into the serum. α₁-antitryspin deficiency (A1AD) leads to uninhibited destruction of elastic fibre by elastase; the main result is pulmonary emphysema.

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