PubMed Health⌕ Search

Biomedical subjects

J-L Pellequer

Publications and source records attributed to J-L Pellequer.

3 recordsLinked to original sources

Structural insights into protein-uranyl interaction: towards an in silico detection method.

Documenting the modes of interaction of uranyl (UO(2)2+) with large biomolecules, and particularly with proteins, is instrumental for the interpretation of its behavior in vitro and in vivo. The gathering of three-dimensional information concerning uranyl-first shell atoms from two structural databases, the Cambridge Structural Databank and the Protein Data Bank (PDB) allowed a screening of corresponding topologies in proteins of known structure. In the computer-aided procedure, all potentially bound residues from the template structure were granted full flexibility using a rotamer library. The Amber force-field was used to loosen constraints and score each predicted site. Our algorithm was validated as a first stage through the recognition of existing experimental data in the PDB. The coherent localization of missing atoms in the density map of an ambiguous uranium/uranyl-protein complex exemplified the efficiency of our approach, which is currently suggesting the experimental investigation of uranyl-protein binding site.

Computers↗

Intrinsic stability and functional properties of disulfide bond-stabilized coagulation factor VIIIa variants.

BACKGROUND: The utility of purified coagulation factor (F)VIII for treatment of hemophilia A is limited in part by its instability following activation by thrombin, which is caused by spontaneous dissociation of the A2 domain from the activated FVIII (FVIIIa) heterotrimer. To prevent this A2 domain dissociation in FVIIIa, we previously engineered a cysteine pair (C664-C1826) in recombinant FVIII that formed a disulfide bond cross-linking the A2 domain in the heavy chain to the A3 domain in the light chain. This engineered disulfide bond resulted in a more stable FVIIIa. AIMS: Here, we characterize the functional parameters of C664-C1828 FVIII and of a new disulfide bond-stabilized FVIII (C662-C1828 FVIII). METHODS: In order to assess whether these FVIII variants might be good candidates for a new therapeutic agent to treat hemophilia A, we investigated a variety of functional parameters that might affect the in vivo properties of the variants, including half-life of disulfide bond-stabilized FVIII and FVIIIa and the potency of these FVIIIa molecules in the FXase complex. RESULTS: Both disulfide bond-stabilized variants had improved affinity for von Willebrand factor (VWF). In studies of FX activation by purified FIXa and FVIIIa, C662-C1828 FVIIIa had normal activity while C664-C1826 FVIIIa had reduced activity. Both C664-C1826 FVIIIa and C662-C1828 FVIIIa were inactivated by activated protein C (APC) but the rates of inactivation were different. CONCLUSION: Overall, the specific location of the disulfide bridge between the A2 and A3 domains appears to affect functional properties of FVIIIa. In summary, introduction of engineered interdomain disulfides results in FVIIIa variants that resist spontaneous loss of activity while retaining susceptibility to APC proteolytic inactivation and maintaining VWF binding.

Factor IXa↗

An engineered interdomain disulfide bond stabilizes human blood coagulation factor VIIIa.

The blood coagulation disorder, hemophilia A, is caused by deficiency of coagulation factor (F)VIII. Hemophilia A is now treated by infusions of pure FVIII, but the activity of FVIII is limited because it is unstable following activation by thrombin. This instability of activated FVIII is the result of dissociation of the A2 subunit. To obtain increased stability in FVIIIa, a disulfide bond between the A2 domain and the A3 domain, preventing A2 subunit dissociation, has been engineered. Structural analysis of the FVIII A domain homology model allowed us to identify residues 664 and 1826 as a potential disulfide bond pair. A FVIII mutant containing Cys664 and Cys1826 was produced and purified (C664-C1826 FVIII). Immunoblotting showed that a disulfide bond did form to link covalently the A2 and the A3 domains. Following activation of the recombinant C664-C1826 FVIII by thrombin, the mutant FVIIIa had increased stability and retained more than 90% of its clotting activity at a time at which wild-type FVIIIa lost more than 90% of its activity. This remarkably stable C664-C1826 FVIIIa provides a unique approach for studies of the cofactor activity of FVIIIa and also for new, improved therapy for hemophilia A.

Amino Acid Substitution↗