This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1ddz
From Proteopedia
|
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 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
Page seeded by OCA on Thu Feb 21 12:15:40 2008
