Abstract
A low molecular mass monomeric protein termed Fh-KTM (Fasciola hepatica Kunitz-type molecule) was isolated from the trematode Fasciola hepatica. Fh-KTM is a single polypeptide of 58 amino acids and a Mr of 6751. The complete amino acid sequence of Fh-KTM was determined and revealed significant similarity to the Kunitz-type (BPTI) family of proteinase inhibitors. Several polymorphisms were observed suggesting that more than one Fh-KTM molecule may be expressed by this parasite. Modified proline residues were shown to occur at all four positions in this protein as 3-hydroxy derivatives. This is the first report of 3-hydroxyproline residues in a Kunitz-type molecule. Indirect immunofluorescence and immunogold labelling revealed that Fh-KTM is an abundant molecule within the parasite localised to the gut, the parenchymal tissue and the tegument of adult F. hepatica. Serine protease inhibition assays revealed that Fh-KTM exhibited little or no inhibition against chymotrypsin, kallikrein, urokinase or key serine proteases of the blood coagulation pathways. However, Fh-KTM was able to inhibit trypsin even though the P1 reactive amino acid of Fh-KTM was a leucine residue.
Original language | English |
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Pages (from-to) | 19-29 |
Number of pages | 11 |
Journal | Molecular and Biochemical Parasitology |
Volume | 74 |
Issue number | 1 |
DOIs | |
Publication status | Published - 1995 |
Externally published | Yes |
Keywords
- 3-Hydroxy proline
- Fasciola hepatica
- Immunolocalisation
- Kunitz