1TPD

STRUCTURES OF THE "OPEN" AND "CLOSED" STATE OF TRYPANOSOMAL TRIOSEPHOSPHATE ISOMERASE, AS OBSERVED IN A NEW CRYSTAL FORM: IMPLICATIONS FOR THE REACTION MECHANISM

1TPD の概要

• エントリーDOI: 10.2210/pdb1tpd/pdb
• 分子名称: TRIOSEPHOSPHATE ISOMERASE (2 entities in total)
• 機能のキーワード: isomerase(intramolecular oxidoreductase)
• 由来する生物種: Trypanosoma brucei brucei
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 53731.66

構造登録者

Noble, M.E.M.,Zeelen, J.Ph.,Wierenga, R.K. (登録日: 1994-02-28, 公開日: 1994-05-31, 最終更新日: 2024-02-14)

主引用文献

Noble, M.E.,Zeelen, J.P.,Wierenga, R.K.
Structures of the "open" and "closed" state of trypanosomal triosephosphate isomerase, as observed in a new crystal form: implications for the reaction mechanism.
Proteins, 16:311-326, 1993

PubMed Abstract: The structure of trypanosomal triosephosphate isomerase (TIM) has been solved at a resolution of 2.1A in a new crystal form grown at pH 8.8 from PEG6000. In this new crystal form (space group C2, cell dimensions 94.8 A, 48.3 A, 131.0 A, 90.0 degrees, 100.3 degrees, 90.0 degrees), TIM is present in a ligand-free state. The asymmetric unit consists of two TIM subunits. Each of these subunits is part of a dimer which is sitting on a crystallographic twofold axis, such that the crystal packing is formed from two TIM dimers in two distinct environments. The two constituent monomers of a given dimer are, therefore, crystallographically equivalent. In the ligand-free state of TIM in this crystal form, the two types of dimer are very similar in structure, with the flexible loops in the "open" conformation. For one dimer (termed molecule-1), the flexible loop (loop-6) is involved in crystal contacts. Crystals of this type have been used in soaking experiments with 0.4 M ammonium sulphate (studied at 2.4 A resolution), and with 40 microM phosphoglycolohydroxamate (studied at 2.5 A resolution). It is found that transfer to 0.4 M ammonium sulphate (equal to 80 times the Ki of sulphate for TIM), gives rise to significant sulphate binding at the active site of one dimer (termed molecule-2), and less significant binding at the active site of the other. In neither dimer does sulphate induce a "closed" conformation. In a mother liquor containing 40 microM phosphoglycolohydroxamate (equal to 10 times the Ki of phosphoglycolohydroxamate for TIM), an inhibitor molecule binds at the active site of only that dimer of which the flexible loop is free from crystal contacts (molecule-2). In this dimer, it induces a closed conformation. These three structures are compared and discussed with respect to the mode of binding of ligand in the active site as well as with respect to the conformational changes resulting from ligand binding.

PubMed: 8356028
DOI: 10.1002/prot.340160402

実験手法

X-RAY DIFFRACTION (2.1 Å)