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You may include any references to papers as in: the use of JSmol in Proteopedia [1] or to the article describing Jmol [2] to the rescue.
The C-reactive protein has been given this name because it precipitates the C polysaccharide in the cell wall.[3]
Structure
CRP structure
Ser53, His95, Cys97, Asp112, Gly113, Gly136, Gly154, Val165, Leu166, Ile171, and Gly196 are the highly conserved residues in the primary sequence of CRP.[3]
The C-reactive protein is a homopentamer of non-covalently bound subunits. Each subunit is a 25 Da protein consisting of 224 residues bound together. The secondary structure is formed of four α-helices and three β-sheets (five-stranded, three-stranded and seven-stranded).[4] The predominant structure is β-sheet [5] but short helical regions can be notice for residues 43 and 185.[3] Residues Glu197 and Lys123 in CRP form an intermolecular ion pair.[6]
Calcium binding-site
CRP is a calcium dependent strcuture. Effectively, Ca2+ is required for PC binding, and more precisely for the formation of the PC binding site. Structural rearrangements of the CRP occur when the protein binds Ca2+. The protection against denaturation and proteolysis is performed through Ca2+ binding too. In the absence of Ca2+, hCRP is cleaved between Asn145 and Phe146 by nagarse protease, and between Phe146 and Glu147 by pronase. [7]
PC binding site
PC stands for phosphocoline. It is a phospholipid in cell membranes and a plasma lipoproteins.[6] Phe-66 and Glu-81 are the two key residues that enable the binding of PC. [3]
Function
Biomedical interest
Healthy humans have CRP rate which is generally about 1 μg/mL.[3] CRP level is 1000 times higher in a cytokine-mediated response due to tissue injury, infection and inflammation. Therefore the CRP rate in serum is common use to detect the activity of a disease.[6] CRP can be defined as a target for the development of cardioprotection and neuroprotection.[3]
Structural highlights
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- ↑ Hanson, R. M., Prilusky, J., Renjian, Z., Nakane, T. and Sussman, J. L. (2013), JSmol and the Next-Generation Web-Based Representation of 3D Molecular Structure as Applied to Proteopedia. Isr. J. Chem., 53:207-216. doi:https://dx.doi.org/10.1002/ijch.201300024
- ↑ Herraez A. Biomolecules in the computer: Jmol to the rescue. Biochem Mol Biol Educ. 2006 Jul;34(4):255-61. doi: 10.1002/bmb.2006.494034042644. PMID:21638687 doi:10.1002/bmb.2006.494034042644
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Kumar, S. V., Ravunny, R. K., Chakraborty, C. (2011), Conserved Domains, Conserved Residues, and Surface Cavities of C-reactive Protein (CRP), Appl Biochem Biotechnol, 165:497–505
- ↑ https://www.uniprot.org/uniprot/P02741
- ↑ https://www.unco.edu/nhs/Chemistry/faculty/dong/pub/pentraxin.pdf
- ↑ 6.0 6.1 6.2 Thompson, D., Pepys, M. B., Wood, S. P. (1999), The physiological structure of human C-reactive protein and its complex with phosphocholine, Structure February 1999, 7:169–177.
- ↑ 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