Sandbox 666: Difference between revisions

    

''Eco''RI (E.C. 3.1.21.4) is a hydrolase and its substrate is a double-strand DNA molecule and two water molecules. For its catalytic activity, ''Eco''RI needs a cofactor, which is the divalent ion Mg²⁺. ''Eco''RI hydrolyses the phosphodiester bond between the guanylic and adenylic residues resulting in 5’-phosphate sticky ends, which are complementary.

== Structure ==

{{STRUCTURE_1eri| PDB=1eri | SCENE= | size='500'}}     

''Eco''RI is composed of two homodimers, so it has two identical subunits (Representation of one <scene name='Sandbox_666/Monomer_structure/4'>subunit</scene>) of 31 kDa, but it is possible to have homotetramers at high concentrations. The constitutive monomers are 276 amino acids long. ''Eco''RI and all the other restriction enzymes show a common structural core, which is a α/β domain. There are several non-contiguous structural elements, whose are involved in DNA recognition<ref name="A">. The constitutive subunits of ''Eco''RI are organized into a single α/β domain (five strands <scene name='Sandbox_666/B_sheet/1'>β</scene> sheet, which is surrounded  by <scene name='Sandbox_666/Helix/1'>two α helices</scene> ). Four of these five β strands are parallel whereas the fourth (β4) is in an anti-parallel orientation to the others<ref name="B">Refinement of Eco RI endonuclease crystal structure: a revised protein chain tracing.