Is Porcine Pancreatic Elastase a Suitable Model for Human Leukocyte Elastase?

Human Leukocyte Elastase (HLE) has recently been implicated as a poor prognostic marker in certain breast cancers and as a key component involved in Chronic Obstructive Pulmonary Diseases. Because HLE is so expensive, Porcine Pancreatic Elastase (PPE) has been used to model elastase activity and inhibition. This paper elucidates the differences and similarities between HLE and PPE through enzyme activity assays, protein sequence alignment, and specificity comparison. In addition, PPE is a nonglycosylated protein which is secreted as a zymogen, where HLE is glycosylated at two positions and is released as a series of isoenzymes. The enzyme activity assays help to prove that HNE and PPE have different substrate specificities. HLE prefers valine while PPE prefers alanine. The two proteins, when aligned using uniprot, show only a 47% similarity.