4HRR

Scapharca tetrameric hemoglobin, CO-state

「1SCT」から置き換えられました

4HRR の概要

• エントリーDOI: 10.2210/pdb4hrr/pdb
• 関連するPDBエントリー: 4hrt
• 分子名称: Globin-2 A chain, Hemoglobin B chain, PROTOPORPHYRIN IX CONTAINING FE, ... (5 entities in total)
• 機能のキーワード: hemoglobin, oxygen transport, globin fold, oxygen
• 由来する生物種: Scapharca inaequivalvis (Inequivalve ark); 詳細
• タンパク質・核酸の鎖数: 8
• 化学式量合計: 135677.96

構造登録者

Royer, W.E. (登録日: 2012-10-28, 公開日: 2013-03-13, 最終更新日: 2024-11-27)

主引用文献

Ronda, L.,Bettati, S.,Henry, E.R.,Kashav, T.,Sanders, J.M.,Royer, W.E.,Mozzarelli, A.
Tertiary and Quaternary Allostery in Tetrameric Hemoglobin from Scapharca inaequivalvis.
Biochemistry, 52:2108-2117, 2013

PubMed Abstract: The clam Scapharca inaequivalvis possesses two cooperative oxygen binding hemoglobins in its red cells: a homodimeric HbI and a heterotetrameric A2B2 HbII. Each AB dimeric half of HbII is assembled in a manner very similar to that of the well-studied HbI. This study presents crystal structures of HbII along with oxygen binding data both in the crystalline state and in wet nanoporous silica gels. Despite very similar ligand-linked structural transitions observed in HbI and HbII crystals, HbII in the crystal or encapsulated in silica gels apparently exhibits minimal cooperativity in oxygen binding, in contrast with the full cooperativity exhibited by HbI crystals. However, oxygen binding curves in the crystal indicate the presence of a significant functional inequivalence of A and B chains. When this inequivalence is taken into account, both crystal and R state gel functional data are consistent with the conservation of a tertiary contribution to cooperative oxygen binding, quantitatively similar to that measured for HbI, and are in keeping with the structural information. Furthermore, our results indicate that to fully express cooperative ligand binding, HbII requires quaternary transitions hampered by crystal lattice and gel encapsulation, revealing greater complexity in cooperative function than the direct communication across a dimeric interface observed in HbI.

PubMed: 23458680
DOI: 10.1021/bi301620x

実験手法

X-RAY DIFFRACTION (1.25 Å)