1GLH image
Deposition Date 1994-11-25
Release Date 1995-02-07
Last Version Date 2024-10-16
Entry Detail
PDB ID:
1GLH
Keywords:
Title:
CATION BINDING TO A BACILLUS (1,3-1,4)-BETA-GLUCANASE. GEOMETRY, AFFINITY AND EFFECT ON PROTEIN STABILITY
Biological Source:
Source Organism:
Host Organism:
Method Details:
Experimental Method:
Resolution:
2.00 Å
R-Value Free:
0.22
R-Value Observed:
0.19
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:1,3-1,4-BETA-GLUCANASE
Chain IDs:A
Chain Length:214
Number of Molecules:1
Biological Source:synthetic construct
Ligand Molecules
Primary Citation
Cation binding to a Bacillus (1,3-1,4)-beta-glucanase. Geometry, affinity and effect on protein stability
Eur.J.Biochem. 222 203 214 (1994)
PMID: 8200344 DOI: 10.1111/j.1432-1033.1994.tb18858.x

Abstact

The hybrid Bacillus (1,3-1,4)-beta-glucanase H(A16-M), consisting of 16 N-terminal amino acids derived from the mature form of the B. amyloliquefaciens enzyme and of 198 C-proximal amino acids from the B. macerans enzyme, binds a calcium ion at a site at its molecular surface remote from the active center [T. Keitel, O. Simon, R. Borriss & U. Heinemann (1993) Proc. Natl Acad. Sci. USA 90, 5287-5291]. X-ray diffraction analysis at 0.22-nm resolution of crystals grown in the absence of calcium and in the presence of EDTA shows this site to be occupied by a sodium ion. Whereas the calcium ion has six oxygen atoms in its coordination sphere, two of which are from water molecules, sodium is fivefold coordinated with a fifth ligand belonging to a symmetry-related protein molecule in the crystal lattice. The affinity of H(A16-M) for calcium over sodium has been determined calorimetrically. Calcium binding stabilizes the native three-dimensional structure of the protein as shown by guanidinium chloride unfolding and thermal inactivation experiments. The enhanced enzymic activity of Bacillus beta-glucanases at elevated temperatures in the presence of calcium ions is attributed to a general stabilizing effect by the cation.

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Primary Citation of related structures