Mechanism of activation of heparin cofactor II by calcium spirulan

作者：Hayakawa Y^*; Hirashima Y; Yamamoto H; Kurimoto M; Hayashi T; Lee JB; Endo S

来源：Archives of Biochemistry and Biophysics, 2003, 416(1): 47-52.

DOI：10.1016/S0003-9861(03)00289-3

• serpin
• heparin cofactor II
• calcium spirulan
• aptamer
• antithrombin
• thrombin

Calcium spirulan (Ca-SP), a novel sulfated polysaccharide, increases the rate of thrombin inhibition by heparin cofactor II (HCII) more than 1000-fold through a mechanism not requiring the amino-terminal acidic domain of HCII. Activation of HCII by Ca-SP was molecular-weight dependent. Furthermore, HD22, an aptamer that binds exosite II of thrombin, produced a concentration-dependent, 15-fold reduction at 5 muM in the rate of thrombin inhibition by HCII with Ca-SP, suggesting that Ca-SP interacts with exosite II of thrombin. Mutations of Lys(173) toLen (K173L) and Arg(189) to Leu (R189L) in the HCII molecule resulted in large decreases in the rate of thrombin inhibition mediated by Ca-SP and in the NaCl concentration needed for elution from Ca-SP-Toyopearl. Mutations of Lys(173) to Arg (K173R) and Arg(189) to Lys (R189K) showed inhibition of thrombin similar to wild-type rHCII (wt-rHCII). These results indicate that Ca-SP binds to the positive charges of Lys 173 and Arg 189 on the HCII molecule. In the thrombin inhibitory process by HCII, Ca-SP appears to play as a template by binding to both thrombin and HCII.

• 出版日期2003-8-1