Sandbox Reserved 1096: Difference between revisions
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So they studied the structure of the PAD2 F221/222A.Ca2+ mutant. It shows an important electron density at all 6 calcium binding sites. All sites are now binding with calcium. Moreover, The active site cysteine, C647 points toward the catalytic center. this conformation is competent for catalysis. It is not the only effect of calcium binding to Ca2 site, it also causes R347 to move out of the active site while W348 moves in to form one wall of the substrate-binding pocket. | So they studied the structure of the PAD2 F221/222A.Ca2+ mutant. It shows an important electron density at all 6 calcium binding sites. All sites are now binding with calcium. Moreover, The active site cysteine, C647 points toward the catalytic center. this conformation is competent for catalysis. It is not the only effect of calcium binding to Ca2 site, it also causes R347 to move out of the active site while W348 moves in to form one wall of the substrate-binding pocket. | ||
[[Image:PAD2.jpg]] | |||
==='''Catalysis of deimination'''=== | ==='''Catalysis of deimination'''=== | ||
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== Citrullination of Arginine residues == | == Citrullination of Arginine residues == | ||
In humans, PAD2 is involved in a type of post-translational modification called citrullination. Indeed, this calcium-dependent enzyme catalyzes a deimination reaction : PAD2 uses one molecule of water to replace the terminal nitrogen of Arginine by an oxygen and a ketone group is formed in place of a ketimine one <ref name="ART1" />. | In humans, PAD2 is involved in a type of post-translational modification called citrullination. Indeed, this calcium-dependent enzyme catalyzes a deimination reaction : PAD2 uses one molecule of water to replace the terminal nitrogen of Arginine by an oxygen and a ketone group is formed in place of a ketimine one <ref name="ART1" />. | ||
The transformation of arginyl residues ([https://fr.wikipedia.org/wiki/Arginine Arginine]), which are positively charged at a neutral pH, into citrullyl residues, which are neutral, leads to the '''''modification of the global charge''''' of the targeted protein. These residue modifications are the result of hydrolysation of guanidinium groups in side chains and may produce important conformational changes in proteins by increasing the hydrophobicity. The catalytic residue which allows hydrolyzation of the guanidium group is a '''''nucleophilic cysteine in position 647'''''. The proper positioning of C647 is due to the binding of calcium ions to PAD 2, essential for deamination reaction. | The transformation of arginyl residues ([https://fr.wikipedia.org/wiki/Arginine Arginine]), which are positively charged at a neutral pH, into citrullyl residues, which are neutral, leads to the '''''modification of the global charge''''' of the targeted protein. These residue modifications are the result of hydrolysation of guanidinium groups in side chains and may produce important conformational changes in proteins by increasing the hydrophobicity. The catalytic residue which allows hydrolyzation of the guanidium group is a '''''nucleophilic cysteine in position 647'''''. The proper positioning of C647 is due to the binding of calcium ions to PAD 2, essential for deamination reaction. | ||
