Thrombin-like snake venom serine protease (PubMed:26227411, PubMed:31131001, PubMed:34506860). Releases fibrinopeptide A and B in the conversion of fibrinogen to fibrin, with preferential activity on the alpha chain of fibrinogen (PubMed:26227411, PubMed:34506860). Also hydrolyzes N-p-toluensulfonyl arginine ester (TAME) and chromogenic artificial substrates of the blood coagulation cascade: S-2222 for factor Xa, S-2302 for kallikrein and S-2238 for thrombin (PubMed:26227411). When tested in vitro, the recombinant protein does not degrade blood clots, suggesting that this toxin lacks fibrinolytic activity (PubMed:31131001). In addition, it moderately inhibits human Kv10.1/KCNH1/EAG1 currents, with a mechanism independent of its enzymatic activity. It selectively blocks Kv10.1/KCNH1/EAG1 in a time and dose-dependent manner (IC(50)=4.2 uM for native protein and IC(50)=2.5 uM for recombinant protein). It may have a preference in interacting with Kv10.1/KCNH1/EAG1 in its closed state, since the inhibitory effect of the toxin is decreased at more depolarized potentials. Corroboratively, it may have possible antitumor applications, since it reduces the viability of human breast cancer cell line MCF7, which strongly expresses Kv10.1/KCNH1/EAG1, but does not affect the liver carcinoma and the non-tumorigenic epithelial breast cell lines, which weakly express Kv10.1/KCNH1/EAG1 (PubMed:32161292). When tested on peripheral blood mononuclear cells (PBMC), the native protein shows mild cytotoxicity, whereas the recombinant protein does not show any cytotoxicity (PubMed:34506860). Native form is not immununogenic, since it does not induce statistically significant antibody production in mice, whereas recombinant form shows an antibody titer slightly higher than the native form (PubMed:34506860). In vivo, subplantar injection in mice paw induces a discreet paw edema (PubMed:31131001). In addition, intraperitoneal injection of the recombinant protein into mice led to fibrinogen depletion, resulting in the blood incoagulability (PubMed:31131001). Inhibited by Cu(2+) and, to a lesser extent, by Zn(2+) and Ba(2+). Not inhibited by Ca(2+) and Mg(2+). Activity is stable from pH 3.5 and 10.5. Thermostable. Activity is stable after incubation at 100 degrees Celsius for 30 min. Monomer. Expressed by the venom gland. Recombinant protein has no activity on many tested channels (Shaker IR, Kv1.4/KCNA4, Kv2.1/KCNB1, hKv11.1/KCNH2/ERG1, rNav1.1/SCN1A, rNav1.2/SCN2A, rNav1.3/SCN3A, rNav1.4/SCN4A, hNav1.5/SCN5A, mNav1.6/SCN8A, hNav1.8/SCN10A). PEGylation of both native and recombinant forms increases 5-6-fold hERG1 inhibition (IC(50)=22.4 uM for PEG-collinein-1 and IC(50)=10.0 uM for PEGrCollinein-1). In contrast, PEGylated proteins displays a great loss in the capability of inhibiting Kv10.1/KCNH1/EAG1, compared to their non-PEGylated counterparts (PubMed:34506860). It is noteworthy that PEGylated proteins have no activity towards all other channels tested (rKv1.1/KCNA1, rKv1.2/KCNA2, rKv1.4/KCNA4, rKv1.6/KCNA6, hKv2.1/KCNB1, hKv3.1/KCNC1, rKv4.2/KCND2, hKv7.2/7.3, hEAG1, Shaker, rNav1.1/SCN1A, rNav1.2/SCN2A, rNav1.3/SCN3A, rNav1.4/SCN4A, hNav1.5/SCN5A, mNav1.6/SCN8A, hNav1.8/SCN10A, rCav3.1/CACNA1G and rCav3.3/CACNA1I) (PubMed:34506860). Both native and recombinant PEGylated forms are also not immununogenic, since they do not induce statistically significant antibody production in mice (PubMed:34506860). Belongs to the peptidase S1 family. Snake venom subfamily.