8RNT: STRUCTURE OF RIBONUCLEASE T1 COMPLEXED WITH ZINC(II) AT 1.8 ANGSTROMS RESOLUTION: A ZN2+.6H2O.CARBOXYLATE CLATHRATE

Citation:
Abstract
In order to study the inhibitory effect of Zn2+ on ribonuclease T1 [RNase T1; Itaya & Inoue (1982). Biochem. J. 207, 357-362], the enzyme was cocrystallized with 2 mM Zn2+, pH 5.2, from a solution containing 55% (v/v) 2-methyl-2,4-pentanediol. The crystals are orthorhombic, P2(1)2(1)2(1), a = 48.71 (1), b = 46.51 (1), c = 41.14 (1) A, Z = 4, V = 93203 A3. The crystal structure was determined by molecular replacement and refined by restrained least-squares methods based on Fhkl for 8291 unique reflections with Fo greater than or equal to 1 sigma (Fo) in the resolution range 10 to 1.8 A and converged at a crystallographic R factor of 0.140. The Zn2+ is not bonded to the active site of RNase T1, probably because the His40 and His92 side chains are protonated. Zn2+ occupies the same site as Ca2+ in a series of crystal structures of free and nucleotide-complexed RNase T1. It is coordinated to Asp15 carboxylate and to six water molecules forming a dodecahedron of square antiprismatic form. The Zn2+...O distances are approximately 2.5 A, suggesting that Zn2+ is clathrated and not coordinated, which would require distances of 2.0 A.
PDB ID: 8RNTDownload
MMDB ID: 58614
PDB Deposition Date: 1991/9/23
Updated in MMDB: 2017/12
Experimental Method:
x-ray diffraction
Resolution: 1.8  Å
Source Organism:
Similar Structures:
Biological Unit for 8RNT: monomeric; determined by author
Molecular Components in 8RNT
Label Count Molecule
Protein (1 molecule)
1
Ribonuclease T1(Gene symbol: AO090011000118)
Molecule annotation
Chemical (1 molecule)
1
1
* Click molecule labels to explore molecular sequence information.

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