1rtc
From Proteopedia
OCA (Talk | contribs)
(New page: 200px<br /><applet load="1rtc" size="450" color="white" frame="true" align="right" spinBox="true" caption="1rtc, resolution 2.3Å" /> '''THE STRUCTURE OF RECO...)
Next diff →
Revision as of 23:44, 20 November 2007
|
THE STRUCTURE OF RECOMBINANT RICIN A CHAIN AT 2.3 ANGSTROMS
Overview
The plant cytotoxin ricin is a heterodimer with a cell surface binding (B), chain and an enzymatically active A chain (RTA) known to act as a specific, N-glycosidase. RTA must be separated from B chain to attack rRNA. The, X-ray structure of ricin has been solved recently; here we report the, structure of the isolated A chain expressed from a clone in Escherichia, coli. This structure of wild-type rRTA has and will continue to serve as, the parent compound for difference Fouriers used to assess the structure, of site-directed mutants designed to analyze the mechanism of this, medically and commercially important toxin. The structure of the, recombinant protein, rRTA, is virtually identical to that seen previously, for A chain in the heterodimeric toxin. Some minor conformational changes, due to interactions with B chain and to crystal packing differences are, described. Perhaps the most significant difference is the presence in rRTA, of an additional active site water. This molecule is positioned to act as, the ultimate nucleophile in the depurination reaction mechanism proposed, by Monzingo and Robertus (1992, J. Mol. Biol. 227, 1136-1145).
About this Structure
1RTC is a Single protein structure of sequence from Ricinus communis. Active as rRNA N-glycosylase, with EC number 3.2.2.22 Full crystallographic information is available from OCA.
Reference
Structure of recombinant ricin A chain at 2.3 A., Mlsna D, Monzingo AF, Katzin BJ, Ernst S, Robertus JD, Protein Sci. 1993 Mar;2(3):429-35. PMID:8453380
Page seeded by OCA on Wed Nov 21 01:51:27 2007
