1r0s: Difference between revisions

[[Image:1r0s.jpg|left|200px]]<br /><applet load="1r0s" size="350" color="white" frame="true" align="right" spinBox="true"  

ADP-ribosyl cyclase catalyzes the elimination of nicotinamide from NAD and cyclization to cADPR, a known second messenger in cellular calcium signaling pathways. We have determined to 2.0 A resolution the structure of Aplysia cyclase with ribose-5-phosphate bound covalently at C3' and with the base exchange substrate (BES), pyridylcarbinol, bound to the active site. In addition, further refinement at 2.4 A resolution of the structure of nicotinamide-bound cyclase, which was previously reported, reveals that ribose-5-phosphate is also covalently bound in this structure, and a second nicotinamide site was identified. The structures of native and mutant Glu179Ala cyclase were also solved to 1.7 and 2.0 A respectively. It is proposed that the second nicotinamide site serves to promote cyclization by clearing the active site of the nicotinamide byproduct. Moreover, a ribosylation mechanism can be proposed in which the cyclization reaction proceeds through a covalently bound intermediate.

1R0S is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aplysia_californica Aplysia californica]. Active as [http://en.wikipedia.org/wiki/NAD(+)_nucleosidase NAD(+) nucleosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.2.5 3.2.2.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1R0S OCA].  

[[Category: Kriksunov, I A.]]

[[Category: Lee, H C.]]

[[Category: Love, M L.]]

[[Category: Szebenyi, D M.E.]]

[[Category: Thiel, D J.]]

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