Elastase

On this page:

• Physical Properties
• Clinical Implications
• Specificity, Kinetics and Activity Determination
• Storage and Stability
• Related Products

Enzyme Commission (EC) Number: 3.4.21.37
Product Number: E8140

Synonyms:

lysosomal elastase, neutrophil elastase, polymorphonuclear leukocyte elastase, serine elastase, lysosomal elastase, granulocyte elastase

Physical Properties

Leukocyte elastase is a 29KDa serine endoprotease of the Proteinase S1 Family. It exists as a single 238 amino acid-peptide chain with four disulfide bonds. The human leukocyte enzyme shares approximately 43% sequence homology with porcine pancreatic elastase. It contains two or thee N-linked glycans of variable composition which account for its three major isoforms.^1,2,3
Isoelectric point: pI = 8.77 - 9.55³

Clinical Implications

Elastase is one of the degradative hydrolases contained in the azurophil granules of phygocytic neutrophils.³

Elevated levels of circulating elastase and/or decreased levels of endogenous inhibitors have been implicated in several inflammatory diseases including arthritis,⁴ Cyclic neutropenia,⁵ Myocardial Ischemia,⁶ Pancreatitis,⁷ Psoriasis,⁸ Pulmonary Emphysema,⁹ and endotoxic shock.¹⁰

Several inhibitors of leukocyte elastase, including elafin, and have been proposed for treatment of related diseases.

Specificity, Kinetics and Activity Determination

Unlike pancreatic elastase the leukocyte enzyme has a preferential cleavage for the carboxyl side of valine, but will also cleave to a lesser extent after alanine.^11,12,13 Natural substrates include elastin,¹⁴ cartilage proteoglycans,¹⁵ collagen types I, II, II and IV^16,17,18 and fibronectin.¹⁹

pH Optimum for activity: 8.5²⁰

Sigma’s Unit Definition: One unit will release one nanomole of p-nitrophenol per second from N-t-BOC-L-alanine p-nitrophenyl ester at pH 6.5 at 37 °C

Method: Continuous Spectrophotometric Rate Determination

In a 3.00 mL reaction mix, the final concentrations are 49 mM sodium phosphate, 0.20 mM N-t-BOC-L-alanine p-nitrophenyl ester, 2% (v/v) acetonitrile, and 1 unit of elastase.

Storage and Stability Detergents such as 0.05-0.2%Triton^® X-100 or 0.1% Brij^® 35 are often included in reaction and extraction buffers to insure solubilization and reduce adhesion to glass particularly at low ionic strength.^2,21

The enzyme retains activity after exposure to 8 M urea and retains 22% of its activity in the presence of 1% SDS. In SDS and 2-mercaptoethanol the enzyme undergoes autolysis giving rise to several low molecular weight fragments.²²

Store lyophilized powder at -20 °C
Once reconstituted, store in frozen aliquots at or below -20 °C