The thermal unfolding of beta 2-Glycoprotein
Beta 2- Glycoprotein I (B2GPI) is an abundant glycoprotein of human plasma. It participates in blood coagulation processes and the clearance of phosphatidylserine exposing- apoptotic cells. B2GPI is also the major antigen involved in the aberrant immune response that characterizes the antiphospholipid syndrome. B2GPI consists of a single chain of 326 aminoacids arranged in five domains. Four of them are the so called sushi or short consensus repeat (SCR) domain with its conserved beta sandwich- arrangement. The fifth domain is larger and it has a lysine rich region that was shown to participate in the interaction of B2GPI with anionic lipids. B2GPI has four N-glycosilation sites with complex bi and triantennary complex glycans containing sialic acid that comprise ~20% of its total weight. To study the folding behavior of this multiple domain glycoprotein we performed differential scanning calorimetry at various pH and salts conditions. We found that at pH 7 the protein unfolding proceeds with a pre-transition at lower temperatures. This effect is more pronounced in the absence of salt. In order to characterize this earlier intermediate we perfomed circular dichroism studies of the thermal unfolding of B2GPI in the far UV region. The transition followed by the far UV signal shows a two state unfolding transition centered at the same temperature of the calorimetric one. This means that the secondary structure of the protein unfolds in a cooperative manner.
| Main Authors: | , , |
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| Format: | Fil: Fil: Bazan, Soledad. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Biológica; Argentina. biblioteca |
| Language: | eng |
| Published: |
2013
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| Subjects: | Differential scanning calorimetry, Circular dichroism, B2GPI, Human plasma, Blood coagulation, |
| Online Access: | http://hdl.handle.net/11086/28231 |
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