1OS3

Dehydrated T6 human insulin at 100 K

1OS3 の概要

• エントリーDOI: 10.2210/pdb1os3/pdb
• 関連するPDBエントリー: 1MSO 3INS 4INS
• 分子名称: Insulin, ZINC ION, CHLORIDE ION, ... (5 entities in total)
• 機能のキーワード: air dried crystal, data measured at 100 k, hormone-growth factor complex, hormone/growth factor
• 由来する生物種: Homo sapiens (human); 詳細
• 細胞内の位置: Secreted: P01308 P01308
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 11837.03

構造登録者

Smith, G.D.,Blessing, R.H. (登録日: 2003-03-18, 公開日: 2003-07-29, 最終更新日: 2024-10-30)

主引用文献

Smith, G.D.,Blessing, R.H.
Lessons from an aged, dried crystal of T(6) human insulin.
Acta Crystallogr.,Sect.D, 59:1384-1394, 2003

PubMed Abstract: The structure of the T(6) hexameric form of human insulin has been determined at both room temperature and 100 K from a single air-dried crystal. At 100 K, the space group is R3 and the asymmetric unit consists of a dimer, as has been observed previously in hydrated structures. At room temperature, the space group is P1 and the unit cell contains a quasi-threefold-symmetric hexamer. In the absence of stabilizing water interactions, the N-termini of all six A chains in the room-temperature structure appear to have undergone partial unfolding, but the N-termini of these chains are well ordered in the 100 K structure. Other differences between the room-temperature and 100 K structures involve the coordination around the zinc ions. At 100 K, both zinc ions clearly exhibit dual coordination: zinc is octahedrally coordinated in one half of the zinc sites but tetrahedrally coordinated in the other half; at room temperature, the electron densities suggest tetrahedral coordination but the bond distances to the fourth ligands are longer than expected. Contrary to what has been observed to date in all other T(6) insulin structures, there are no contacts between pairs of GluB13 residues, either at room temperature or at 100 K, that would suggest the presence of a hydrogen bond. At room temperature, three of the six independent GluB13 side chains are disordered; at 100 K, both independent side chains are disordered. The disorder in the GluB13 side chains and the lack of contacts between carboxylate groups suggests that as a result of disruption of the hydration structure in the central core of the hexamer, all six B13 carboxylates bear a negative charge. This in turn suggests that in the hydrated structures the well ordered water structure in the central core is involved in stabilizing the B13 side-chain conformations and modulating charge repulsions among the six B13 glutamates if they are not protonated, or that, as is considered more likely, the water structure plays an important role in modulating the pK(a) values of the B13 glutamates, resulting in protonation and hydrogen-bond formation.

PubMed: 12876340
DOI: 10.1107/S090744490301165X

実験手法

X-RAY DIFFRACTION (1.95 Å)