1ddz
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(New page: 200px<br /> <applet load="1ddz" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ddz, resolution 2.2Å" /> '''X-RAY STRUCTURE OF A...)
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Revision as of 06:51, 18 November 2007
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X-RAY STRUCTURE OF A BETA-CARBONIC ANHYDRASE FROM THE RED ALGA, PORPHYRIDIUM PURPUREUM R-1
Overview
The carbonic anhydrases (CAs) fall into three evolutionarily distinct, families designated alpha-, beta-, and gamma-CAs based on their primary, structure. beta-CAs are present in higher plants, algae, and prokaryotes, and are involved in inorganic carbon utilization. Here, we describe the, novel x-ray structure of beta-CA from the red alga, Porphyridium, purpureum, at 2.2-A resolution using intrinsic zinc multiwavelength, anomalous diffraction phasing. The CA monomer is composed of two, internally repeating structures, being folded as a pair of fundamentally, equivalent motifs of an alpha/beta domain and three projecting, alpha-helices. The motif is obviously distinct from that of either alpha-, or gamma-CAs. This homodimeric CA appears like a tetramer with a pseudo, 222 symmetry. The active site zinc is coordinated by a Cys-Asp-His-Cys, tetrad that is strictly conserved among the beta-CAs. No water molecule is, found in a zinc-liganding radius, indicating that the zinc-hydroxide, mechanism in alpha-CAs, and possibly in gamma-CAs, is not directly, applicable to the case in beta-CAs. Zinc coordination environments of the, CAs provide an interesting example of the convergent evolution of distinct, catalytic sites required for the same CO(2) hydration reaction.
About this Structure
1DDZ is a Single protein structure of sequence from Porphyridium purpureum with ZN as ligand. The following page contains interesting information on the relation of 1DDZ with [Carbonic Anhydrase]. Active as Carbonate dehydratase, with EC number 4.2.1.1 Full crystallographic information is available from OCA.
Reference
X-ray structure of beta-carbonic anhydrase from the red alga, Porphyridium purpureum, reveals a novel catalytic site for CO(2) hydration., Mitsuhashi S, Mizushima T, Yamashita E, Yamamoto M, Kumasaka T, Moriyama H, Ueki T, Miyachi S, Tsukihara T, J Biol Chem. 2000 Feb 25;275(8):5521-6. PMID:10681531
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