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N-glycans and the N terminus of protein C inhibitor affect the cofactor-enhanced rates of thrombin inhibition

Sun, Wei; Parry, Simon; Panico, Maria; Morris, Howard R; Kjellberg, Margareta LU ; Engström, Åke; Dell, Anne and Schedin-Weiss, Sophia (2008) In Journal of Biological Chemistry 283(27). p.18601-18611
Abstract
Protein C inhibitor (PCI) is a serine protease inhibitor, displaying broad protease specificity, found in blood and other tissues. In blood, it is capable of inhibiting both procoagulant and anticoagulant proteases. Mechanisms that provide specificity to PCI remain largely unrevealed. In this study we have for the first time provided a full explanation for the marked size heterogeneity of blood-derived PCI and identified functional differences between naturally occurring PCI variants. The heterogeneity was caused by differences in N-glycan structures, N-glycosylation occupancy, and the presence of a Delta 6-N-cleaved form. Bi-, tri-, and tetra-antennary complex N-glycans were identified. Fucose residues were identified both on the core... (More)
Protein C inhibitor (PCI) is a serine protease inhibitor, displaying broad protease specificity, found in blood and other tissues. In blood, it is capable of inhibiting both procoagulant and anticoagulant proteases. Mechanisms that provide specificity to PCI remain largely unrevealed. In this study we have for the first time provided a full explanation for the marked size heterogeneity of blood-derived PCI and identified functional differences between naturally occurring PCI variants. The heterogeneity was caused by differences in N-glycan structures, N-glycosylation occupancy, and the presence of a Delta 6-N-cleaved form. Bi-, tri-, and tetra-antennary complex N-glycans were identified. Fucose residues were identified both on the core GlcNAc and as parts of sialyl-Le(a/x) epitopes. Moreover, a glycan with a composition that implied a di-sialyl antenna was observed. PCI was N-glycosylated at all three potential N-glycosylation sites, Asn-230, Asn-243, and Asn-319, but a small fraction of PCI lacked the N-glycan at Asn-243. The overall removal of N-glycans affected the maximal heparin- and thrombomodulin-enhanced rates of thrombin inhibition differently in different solution conditions. In contrast, the Delta 6-N-region increased both the heparin- and the thrombomodulin-enhanced rates of thrombin inhibition at all conditions examined. These results thus demonstrate that the N-linked glycans and the N-terminal region of blood-derived PCI in different ways affect the cofactor-enhanced rates of thrombin inhibition and provide information on the mechanisms by which this may be achieved. The findings are medically important, in view of the documented association of PCI with atherosclerotic plaques and the promising effect of PCI on reducing hypercoagulability states. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Biological Chemistry
volume
283
issue
27
pages
18601 - 18611
publisher
ASBMB
external identifiers
  • wos:000257165600016
  • scopus:49649093374
ISSN
1083-351X
DOI
10.1074/jbc.M800608200
language
English
LU publication?
yes
id
87b41240-1633-45e5-85de-c5254bd8bb1b (old id 1186859)
date added to LUP
2008-09-04 09:24:27
date last changed
2017-07-30 03:37:37
@article{87b41240-1633-45e5-85de-c5254bd8bb1b,
  abstract     = {Protein C inhibitor (PCI) is a serine protease inhibitor, displaying broad protease specificity, found in blood and other tissues. In blood, it is capable of inhibiting both procoagulant and anticoagulant proteases. Mechanisms that provide specificity to PCI remain largely unrevealed. In this study we have for the first time provided a full explanation for the marked size heterogeneity of blood-derived PCI and identified functional differences between naturally occurring PCI variants. The heterogeneity was caused by differences in N-glycan structures, N-glycosylation occupancy, and the presence of a Delta 6-N-cleaved form. Bi-, tri-, and tetra-antennary complex N-glycans were identified. Fucose residues were identified both on the core GlcNAc and as parts of sialyl-Le(a/x) epitopes. Moreover, a glycan with a composition that implied a di-sialyl antenna was observed. PCI was N-glycosylated at all three potential N-glycosylation sites, Asn-230, Asn-243, and Asn-319, but a small fraction of PCI lacked the N-glycan at Asn-243. The overall removal of N-glycans affected the maximal heparin- and thrombomodulin-enhanced rates of thrombin inhibition differently in different solution conditions. In contrast, the Delta 6-N-region increased both the heparin- and the thrombomodulin-enhanced rates of thrombin inhibition at all conditions examined. These results thus demonstrate that the N-linked glycans and the N-terminal region of blood-derived PCI in different ways affect the cofactor-enhanced rates of thrombin inhibition and provide information on the mechanisms by which this may be achieved. The findings are medically important, in view of the documented association of PCI with atherosclerotic plaques and the promising effect of PCI on reducing hypercoagulability states.},
  author       = {Sun, Wei and Parry, Simon and Panico, Maria and Morris, Howard R and Kjellberg, Margareta and Engström, Åke and Dell, Anne and Schedin-Weiss, Sophia},
  issn         = {1083-351X},
  language     = {eng},
  number       = {27},
  pages        = {18601--18611},
  publisher    = {ASBMB},
  series       = {Journal of Biological Chemistry},
  title        = {N-glycans and the N terminus of protein C inhibitor affect the cofactor-enhanced rates of thrombin inhibition},
  url          = {http://dx.doi.org/10.1074/jbc.M800608200},
  volume       = {283},
  year         = {2008},
}