Sandbox Reserved 1121: Difference between revisions

From Proteopedia
Jump to navigationJump to search
No edit summary
No edit summary
Line 15: Line 15:
=== Ca<sup>2+</sup> binding-site ===
=== Ca<sup>2+</sup> binding-site ===
CRP is a calcium dependent structure. Effectively, Ca<sup>2+</sup> is required for PC binding, and more precisely for the formation of the PC binding site thanks to structural rearrangements. The protection against denaturation and proteolysis is performed through Ca<sup>2+</sup> binding too. In the absence of Ca<sup>2+</sup>, hCRP is cleaved between Asn145 and Phe146 by nagarse protease, and between Phe146 and Glu147 by pronase.  
CRP is a calcium dependent structure. Effectively, Ca<sup>2+</sup> is required for PC binding, and more precisely for the formation of the PC binding site thanks to structural rearrangements. The protection against denaturation and proteolysis is performed through Ca<sup>2+</sup> binding too. In the absence of Ca<sup>2+</sup>, hCRP is cleaved between Asn145 and Phe146 by nagarse protease, and between Phe146 and Glu147 by pronase.  
Asp60, Asn61, Glu138, Asp140 and the main-chain carbonyl of Gln139 residues allow the first calcium ion binding, and the second is performed through Glu138, Asp140, Glu147 and Gln150 <ref name="ramadan">Ramadan, M. A. M., Shrive, A. K., Holden, D., Myles, D. A. A., Volanakis, J. E.,  Larry J.DeLucas, L. J., Greenhough, T. J. (2002), The three-dimensional structure of calcium-depleted human C-reactive protein from perfectly twinned crystals, Acta Cryst., D58 :992-1001</ref>.
Asp60, Asn61, Glu138, Asp140 and the main-chain carbonyl of Gln139 residues allow the first calcium ion binding, and the second is performed through Glu138, Asp140, Glu147 and Gln150 <ref name="ramadan">PMID: 12037301</ref>.
The two Ca<sup>2+</sup>-binding sites are overlapping in a loop. In the absence of Ca<sup>2+</sup>, the loop changes conformaion and releases the proteolysis site. Therefore Ca<sup>2+</sup> protects CRP form proteolytic cleavage <ref name="agrawal"/>.
The two Ca<sup>2+</sup>-binding sites are overlapping in a loop. In the absence of Ca<sup>2+</sup>, the loop changes conformaion and releases the proteolysis site. Therefore Ca<sup>2+</sup> protects CRP form proteolytic cleavage <ref name="agrawal"/>.