Expression and characterization of haemathrins, madanin-like thrombin inhibitors, isolated from the salivary gland of tick Haemaphysalis bispinosa (Acari: Ixodidae)

Study on Structure Activity Relationship of Natural Flavonoids against Thrombin by Molecular Docking Virtual Screening Combined with Activity Evaluation In Vitro

“…Molecular docking technology, an algorithm that predicts the putative geometry of a protein-ligand complex has been successfully applied in the studies of SAR of compounds and TCM as well as predicting binding affinities of ligands [18][19][20][21][22]. Irrespective of these gains, there also exist disadvantages such as low accuracy and high false positive rate.…”

Acquired tick resistance: The trail is hot

“…60 Other anticoagulants from Ixodes ticks include metalloproteases, [61][62][63][64] various serpins, 52,65,66 Ir-CPI, 67 Iris 68 and Rhippilin-1 and -2 from Rhipicephalus hemaphysaloides. 69 Haemaphysalis ticks have a particularly large number of demonstrated and putative thrombin inhibitors, including: madanin-1 and -2, 70,71 chimadanin, 72 and the serpin HLS1 73 from Haemaphysalis longicornis; haemathrin from Haemaphysalis bispinosa 74 ; and serpins HDS1 and HDS2 from H. doenitzi 75 Iris from I. ricinus 68 has also demonstrated anti-thrombin activity, in addition to BmGTI, 76 the serpin RmS-15, 77 BmAP, 78 and microphilin 79 from R. microplus. Haemaphysalis proteins longistatin 80 and enolase 81 stimulate this pathway by activating plasminogen that negatively regulates the coagulation cascade.…”

Chemical synthesis of a haemathrin sulfoprotein library reveals enhanced thrombin inhibition following tyrosine sulfation

“…IC 50 values of 40-46 mM reported for the recombinant material). 19 Interestingly, sulfation at Y31 was found to impart a dramatic improvement in activity (ca. 1.5 orders of magnitude) for both singly sulfated variants of haemathrin-1 3 (K i = 13 nM) and haemathrin-2 6 (K i = 18 nM).…”

“…These proteins have been previously identified via PCR amplification and recombinant variants expressed in bacteria were shown to exhibit thrombin inhibitory activity, albeit in unmodified form. 18,19 Based on the sequence similarity to madanin-1, a salivary protein from Haemaphysalis longicornis (known to be sulfated) 15 together with the presence of conserved Tyr residues flanked by a number of acidic aspartate (Asp) and glutamate (Glu) amino acids (a known recognition motif for TPSTs), 20,21 we postulated that both haemathrin-1 (1) and haemathrin-2 (2) are post-translationally sulfated at Y31 and Y34 ( Fig. 1).…”

“…Syntheses of the C-terminal fragments were achieved using Fmoc-strategy solid-phase peptide synthesis (SPPS) wherein sTyr residues were installed at positions Y31 and Y34 using the commercially available Fmoc-Tyr(SO 3 nP)-OH building block 9. Selenylated building blocks Boc-(g-SePMB)Glu-OH (10) and Boc-(b-SePMB)Asp-OH (11) were coupled as the N-terminal residues to afford resin-bound haemathrin-1 (12-15) and haemathrin-2 (16)(17)(18)(19) fragments, respectively. Each of the peptides were then deprotected and cleaved from resin using an acidic cocktail followed by PMB deprotection (see ESI, † for full synthetic details).…”