FLAVOCETIN-A AND FLAVOCETIN-B, 2 HIGH-MOLECULAR-MASS GLYCOPROTEIN IB BINDING-PROTEINS WITH HIGH-AFFINITY PURIFIED FROM TRIMERESURUS-FLAVOVIRIDIS VENOM, INHIBIT PLATELET-AGGREGATION AT HIGH-SHEAR STRESS

Citation
Y. Taniuchi et al., FLAVOCETIN-A AND FLAVOCETIN-B, 2 HIGH-MOLECULAR-MASS GLYCOPROTEIN IB BINDING-PROTEINS WITH HIGH-AFFINITY PURIFIED FROM TRIMERESURUS-FLAVOVIRIDIS VENOM, INHIBIT PLATELET-AGGREGATION AT HIGH-SHEAR STRESS, Biochimica et biophysica acta (G). General subjects, 1244(2-3), 1995, pp. 331-338
Citations number
40
Categorie Soggetti
Biology,Biophysics
ISSN journal
03044165
Volume
1244
Issue
2-3
Year of publication
1995
Pages
331 - 338
Database
ISI
SICI code
0304-4165(1995)1244:2-3<331:FAF2HG>2.0.ZU;2-B
Abstract
Two high molecular mass proteins, flavocetin-A and flavocetin-B, were purified from Trimeresurus flavoviridis venom. On polyacrylamide gel e lectrophoresis in the presence of sodium dodecyl sulfate, the apparent molecular mass of flavocetin-A and -B were 149 and 139 kDa, respectiv ely, under nonreducing conditions. On reduction, flavocetin-A showed t wo distinct subunits (17 and 14 kDa), and flavocetin-B three distinct subunits (17, 15 and 14 kDa). At 1 mu g/ml, flavocetin-A and -B (flavo cetins) inhibited the van Willebrand factor (vWF)-dependent aggregatio n of fixed human platelets. However, flavocetins (10 mu g/ml) had no e ffect on ADP- and collagen-induced platelet aggregation in PRP. Flavoc etins (3 mu g/ml) also inhibited shear-induced platelet aggregation at high shear stress, Furthermore, flavocetin-A completely inhibited the aggregation of and ATP release from washed platelets stimulated with a low concentration of thrombin. Flavocetin-A specifically bound to pl atelet with high affinity (K-d = 0.35 +/- 0.13 nM) at 21 500 +/- 1760 binding sites per platelet. The N-terminal amino acid sequences of the subunits of flavocetin-A shaw a high degree of homology with those of echicetin, botrocetin, alboaggregin-B and factor IX/factor X-binding protein. These results suggest that flavocetins may be a useful tool f or further investigation of the GPIb-VWF interaction.