Characterisation of tryptase and a granzyme H-like chymase isolated from equine mastocytoma tissue.

This research focuses on detailing the properties of two protein-related compounds found in horse mast cell tissues. The major findings include the identification of a substance similar to human tryptase-beta and another resembling human granzyme H, both of which are significant in the context of allergic reactions.

Objective of the Study

• This research aims to investigate and elucidate the characteristics of proteinases (proteolysis-inducing enzymes) found within equine mast cells. Prior to this study, there has been little to no exploration of this topic.

Methods and Findings

• Two proteolytic components from horse mastocytoma tissue were identified using substrates for trypsin and chymotrypsin.
• Through chromatographic purification, the trypsin-like component was found to be an equine mast cell tryptase. This was established by determining the N-terminal amino acid sequence.
• This substance was found to bear a close resemblance to human tryptase-beta, sharing 85% identity over 20 residues. It also shared similar molecular size and cleavage specificity to human tryptase-beta.
• A second substance, a 32kDa chymotrypsin-like component, was also isolated from the mastocytoma extract. This compound was named equine mast cell proteinase-1 (eqMCP-1).
• The N-terminal amino acid sequence of eqMCP-1 was discovered to be quite similar to human granzyme H, having 95% resemblance over 19 residues.

Implications and Usage

• The researchers generated rabbit antisera (blood serum containing antibodies) directed against both the tryptase and eqMCP-1. Through immunohistochemistry, these antisera succeeded in detecting equine mast cells.
• The development and use of these antibodies will be vital in future clinical studies, especially when looking into the role of mast cell proteinases in equine allergic diseases.