In addition to snakes, our lab has been working on ticks in the last decade. Ticks are blood feeding animals which require blood meals for their survival. In order to do this, they inject their saliva into the site of feeding on their host.

Identification of novel bioactive peptides from tick saliva:
Our group is interested in identifying biomolecules present in the saliva of the ticks, particularly anticoagulant and anti-platelet peptides. As the amount of saliva is extremely minute and limited, we have developed an on-line inhibition assay which is coupled to a nano-LC and mass spectrometer. This allows us to simultaneously purify and identify anticoagulants which are present in small amounts in a complex mixture.

Variegin:
We have successfully isolated and characterized an anti-coagulant peptide named variegin from the saliva of Amblyomma variegatum, the tropical bont tick. Variegin is a potent Thrombin inhibitor with a strong affinity for the enzyme (Ki = 10.4 pM). The three-dimensional crystal structure shows variegin binding to the Thrombin active site and exosite-I. Upon binding to thrombin, variegin is cleaved. This cleavage product still retained strong binding to the thrombin exosite-I (Ki = 14.1 nM), resulting in the prolonged inhibition of the enzyme.

Transcriptomics and proteomics of tick saliva:
We are also interested in the transcriptome and the proteome of ticks, as well as the sexual differences in expression of salivary proteins between male and female ticks.

In collaboration with others, we have worked on toxins from scorpion, spider, conus and fish venoms.  We have identified, isolated and characterized a number of new toxins. We have determined their structure-function relationships and folding determinants.

α- and λ/χ-conotoxins

k-Hefutoxin1

 

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