Heparin binding site, conformational change, and activation of antithrombin

Evans, Dyfed L.; Marshall, Craig J.; Christey, Peter B.; Carrell, Robin W.

doi:10.1021/bi00165a013

Cited by 61 publications

(45 citation statements)

References 59 publications

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“…However, some possible mechanisms have been postulated by others (8,15): i) GAGs may bind to enzymes inducing a conformational change, leading to a more or less active form; ii) GAGs may bind to natural substrates or inhibitors, neutralizing their positive charges and interfering with their hydrolysis or inhibition.…”

Section: Gagsmentioning

confidence: 99%

Glycosaminoglycans affect the interaction of human plasma kallikrein with plasminogen, factor XII and inhibitors

Gozzo

Nunes

Nader

et al. 2003

Braz J Med Biol Res

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Human plasma kallikrein, a serine proteinase, plays a key role in intrinsic blood clotting, in the kallikrein-kinin system, and in fibrinolysis. The proteolytic enzymes involved in these processes are usually controlled by specific inhibitors and may be influenced by several factors including glycosaminoglycans, as recently demonstrated by our group. The aim of the present study was to investigate the effect of glycosaminoglycans (30 to 250 µg/ml) on kallikrein activity on plasminogen and factor XII and on the inhibition of kallikrein by the plasma proteins C1-inhibitor and antithrombin. Almost all available glycosaminoglycans (heparin, heparan sulfate, bovine and tuna dermatan sulfate, chondroitin 4-and 6-sulfates) reduced (1.2 to 3.0 times) the catalytic efficiency of kallikrein (in a nanomolar range) on the hydrolysis of plasminogen (0.3 to 1.8 µM) and increased (1.9 to 7.7 times) the enzyme efficiency in factor XII (0.1 to 10 µM) activation. On the other hand, heparin, heparan sulfate, and bovine and tuna dermatan sulfate improved (1.2 to 3.4 times) kallikrein inhibition by antithrombin (1.4 µM), while chondroitin 4-and 6-sulfates reduced it (1.3 times). Heparin and heparan sulfate increased (1.4 times) the enzyme inhibition by the C1-inhibitor (150 nM).

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Section: Gagsmentioning

confidence: 99%

Glycosaminoglycans affect the interaction of human plasma kallikrein with plasminogen, factor XII and inhibitors

Gozzo

Nunes

Nader

et al. 2003

Braz J Med Biol Res

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“…This form of ATIII is cleaved between Ser 386 and Thr 387 and can be generated by digesting with porcine elastase (20). Other enzymes can cleave ATIII and produce additional R forms such as thrombin (Arg 394 -Ser 395 ), pancreatic elastase (Val 388 -Iso 389 ) and human neutrophil elastase (Iso 391 -Ala 392 ) (26,27). A "pre-latent" antithrombin with anti-angiogenic activity has also been described in which the antithrombin activity and a high heparin binding affinity are preserved (21).…”

Section: A Modified Form Of Atii Is Purified From Ctl Cultures As An mentioning

confidence: 99%

Purification of a Modified Form of Bovine Antithrombin III as an HIV-1 CD8+ T-cell Antiviral Factor

Geiben-Lynn

Brown

Walker

et al. 2002

Journal of Biological Chemistry

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CD8 ؉ T-cells secrete soluble factor(s) capable of inhibiting both R5-and X4-tropic strains of human immunodeficiency virus type 1 (HIV-1). CCR5 chemokine ligands, released from activated CD8 ؉ T-cells, contribute to the antiviral activity of these cells. These CC-chemokines, however, do not account for all CD8 ؉ T-cell antiviral factor(s) (CAF) released from these cells, particularly because the elusive CAF can inhibit the replication of X4 HIV-1 strains that use CXCR4 and not CCR5 as a coreceptor. Here we demonstrate that activated CD8 ؉ T-cells of HIV-1-seropositive individuals modify serum bovine antithrombin III into an HIV-1 inhibitory factor capable of suppressing the replication of X4 HIV-1. These data indicate that antithrombin III may play a role in the progression of HIV-1 disease.Soluble inhibitory factors produced by CD8 ϩ T-cells have been shown to inhibit HIV-1 1 replication and may play a critical role in vivo in antiviral host defense (1). These inhibitory factors include CC-chemokines (2-4), which bind to the CCR5 coreceptor and inhibit R5 viral entry into cells (1) (5-7), as well as less well characterized soluble factor(s) produced by CD8 ϩ T-cells and termed CD8 ϩ T-cell antiviral factor(s) (CAF), which are capable of inhibiting both R5 and X4 .Recently, we demonstrated that there are two factors produced by activated CD8 ϩ T-cells capable of inhibiting the X4 strain HIV-1 IIIB (16). These factors are distinctive in size and the ability to bind heparin. One of these factors bound heparin at physiological salt concentration, eluted at 350 mM NaCl, and was retained by a 50-kDa cut-off Centricon filter. The other factor did not bind heparin at physiological salt concentration and was filtered through a 50-kDa cut-off Centricon filter. The HIV-1 inhibitory activity of these factors was higher with bulk CD8 ϩ T-cells of seropositive individuals and HIV-1-specific cytotoxic T-lymphocytes (CTL) compared with bulk CD8 ϩ Tcells of HIV-1-seronegative individuals (16). In the present study we identified the heparin binding inhibitory activity as a CD8 ϩ T-cell modified form of antithrombin, which is produced in higher amounts by HIV-1-specific CTL and bulk CD8 ϩ Tcells of seropositive individuals than by bulk CD8 ϩ T-cells of seronegative individuals. In this study for the first time we demonstrate that CD8 ϩ T-cells can activate a serum protein to become inhibitory for HIV, a possibility that has not been addressed previously. EXPERIMENTAL PROCEDURESHIV-specific CTL Clones and Bulk CD8 ϩ T-Cells-Polyclonal CD8 ϩ cells that were 90 -99% CD3 ϩ -and CD8 ϩ -positive were generated by fluorescence-activated cell sorting from the six seronegative and six HIV-1-seropositive long-term nonprogressors by positive selection with anti-CD8 antibody-coated immunomagnetic beads (PerSeptive Biosystems, Framingham, MA) as described (16). HIV-1-specific CTL clones were used as described (16). Bulk CD8 ϩ cell lines from seropositive and seronegative persons were established by incubating purified CD8 ϩ cells (2 ϫ 10 6 )...

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“…Heparin has been known to enhance the inhibitory activity of most heparin-binding serpins toward their target proteinases (36,37). The mechanisms have been explained by a ternary complex and an allosteric model (37)(38)(39)(40). Unlike other heparin-binding serpins, the inhibitory activity of kallistatin toward tissue kallikrein is distinctively abolished by heparin.…”

Section: P1 P2 and P3 Specificity Of Kallistatinmentioning

confidence: 99%

Roles of the P1, P2, and P3 Residues in Determining Inhibitory Specificity of Kallistatin toward Human Tissue Kallikrein

Chen

Chao

2000

Journal of Biological Chemistry

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Kallistatin is a serpin with a unique P1 Phe, which confers an excellent inhibitory specificity toward tissue kallikrein. In this study, we investigated the P3-P2-P1 residues (residues 386 -388) of human kallistatin in determining inhibitory specificity toward human tissue kallikrein by site-directed mutagenesis and molecular modeling. Human kallistatin mutants with 19 different amino acid substitutions at each P1, P2, or P3 residue were created and purified to compare their kallikrein binding activity. Complex formation assay showed that P1 Arg, P1 Phe (wild type), P1 Lys, P1 Tyr, P1 Met, and P1 Leu display significant binding activity with tissue kallikrein among the P1 variants. Kinetic analysis showed the inhibitory activities of the P1 mutants toward tissue kallikrein in the order of P1 Arg > P1 Phe > P1 Lys > P1 Tyr > P1 Leu > P1 Met. P1 Phe displays a better selectivity for human tissue kallikrein than P1 Arg, since P1 Arg also inhibits several other serine proteinases. Heparin distinguishes the inhibitory specificity of kallistatin toward kallikrein versus chymotrypsin. For the P2 and P3 variants, the mutants with hydrophobic and bulky amino acids at P2 and basic amino acids at P3 display better binding activity with tissue kallikrein. The inhibitory activities of these mutants toward tissue kallikrein are in the order of P2 Phe (wild type) > P2 Leu > P2 Trp > P2 Met and P3 Arg > P3 Lys (wild type). Molecular modeling of the reactive center loop of kallistatin bound to the reactive crevice of tissue kallikrein indicated that the P2 residue required a long and bulky hydrophobic side chain to reach and fill the hydrophobic S2 cleft generated by

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Heparin binding site, conformational change, and activation of antithrombin

Cited by 61 publications

References 59 publications

Glycosaminoglycans affect the interaction of human plasma kallikrein with plasminogen, factor XII and inhibitors

Glycosaminoglycans affect the interaction of human plasma kallikrein with plasminogen, factor XII and inhibitors

Purification of a Modified Form of Bovine Antithrombin III as an HIV-1 CD8+ T-cell Antiviral Factor

Roles of the P1, P2, and P3 Residues in Determining Inhibitory Specificity of Kallistatin toward Human Tissue Kallikrein

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