Article Abstract:
Two domains ( one and two) were detected in the crystal structure of the T7 (adenosine triphosphate) ATP-dependent deoxyribonucleotide acid (DNA) ligase at 2.6 amstrong resolution. Domain one is composed of three antiparallel beta sheets with six alpha helices. The ATP-binding site is located beneath the beta sheets. Domain two is composed of a fold of highly twisted antiparallel beta sheets with a single alpha helix along the one edge. The two domain structure of T7 DNA ligase is similar with DNA methyltransferases due to the presence of a groove between the domains.
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Article Abstract:
X-ray crystallography was utilized to determine the conformation of the two forms of guanosine triphosphate (GTP) complex of the guanosine monophosphate-enzyme adduct and the PCBV-1 capping enzyme. Structure determination and refinement of the two conformations of the messenger RNA capping enzyme at 2.5 angstrom resolution indicated the ability of the open conformation to accommodate the RNA substrate. On the other hand, the closed form of the capping enzyme can be guanylated in the presence of excess GTP and manganese ions.
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Article Abstract:
A study was conducted to determine two different structures of PcrA DNA helicase complexed supporting the same single strand tailed DNA duplex. One of the structures had a nonhydrolyzable analog of ATP while the other contained a bound sulphate ion sitting in a position equivalent to that occupied by the phosphate ion generated after ATP hydrolysis. Full-length PcrA protein was utilized to prepare a crystal of the PcrA/DNA/ADPNP complex.
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