1DDZ

X-RAY STRUCTURE OF A BETA-CARBONIC ANHYDRASE FROM THE RED ALGA, PORPHYRIDIUM PURPUREUM R-1

Summary for 1DDZ

• Entry DOI: 10.2210/pdb1ddz/pdb
• Descriptor: CARBONIC ANHYDRASE, ZINC ION (3 entities in total)
• Functional Keywords: alpha-beta-alpha, lyase
• Biological source: Porphyridium purpureum
• Total number of polymer chains: 2
• Total formula weight: 110248.56

Authors

Mitsuhashi, S.,Mizushima, T.,Yamashita, E.,Miyachi, S.,Tsukihara, T. (deposition date: 1999-11-12, release date: 2000-03-08, Last modification date: 2024-02-07)

Primary citation

Mitsuhashi, S.,Mizushima, T.,Yamashita, E.,Yamamoto, M.,Kumasaka, T.,Moriyama, H.,Ueki, T.,Miyachi, S.,Tsukihara, T.
X-ray structure of beta-carbonic anhydrase from the red alga, Porphyridium purpureum, reveals a novel catalytic site for CO(2) hydration.
J.Biol.Chem., 275:5521-5526, 2000

PubMed Abstract: 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.

PubMed: 10681531
DOI: 10.1074/jbc.275.8.5521

Experimental method

X-RAY DIFFRACTION (2.2 Å)