1glh
From Proteopedia
(New page: 200px<br /><applet load="1glh" size="450" color="white" frame="true" align="right" spinBox="true" caption="1glh, resolution 2.0Å" /> '''CATION BINDING TO A B...) |
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| - | [[Image:1glh.gif|left|200px]]<br /><applet load="1glh" size=" | + | [[Image:1glh.gif|left|200px]]<br /><applet load="1glh" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1glh, resolution 2.0Å" /> | caption="1glh, resolution 2.0Å" /> | ||
'''CATION BINDING TO A BACILLUS (1,3-1,4)-BETA-GLUCANASE. GEOMETRY, AFFINITY AND EFFECT ON PROTEIN STABILITY'''<br /> | '''CATION BINDING TO A BACILLUS (1,3-1,4)-BETA-GLUCANASE. GEOMETRY, AFFINITY AND EFFECT ON PROTEIN STABILITY'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The hybrid Bacillus (1,3-1,4)-beta-glucanase H(A16-M), consisting of 16 | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 1GLH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Synthetic_construct Synthetic construct] with NA as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Licheninase Licheninase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.73 3.2.1.73] Full crystallographic information is available from [http:// | + | 1GLH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Synthetic_construct Synthetic construct] with <scene name='pdbligand=NA:'>NA</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Licheninase Licheninase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.73 3.2.1.73] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GLH OCA]. |
==Reference== | ==Reference== | ||
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[[Category: hydrolase]] | [[Category: hydrolase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:51:22 2008'' |
Revision as of 10:51, 21 February 2008
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CATION BINDING TO A BACILLUS (1,3-1,4)-BETA-GLUCANASE. GEOMETRY, AFFINITY AND EFFECT ON PROTEIN STABILITY
Overview
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.
About this Structure
1GLH is a Single protein structure of sequence from Synthetic construct with as ligand. Active as Licheninase, with EC number 3.2.1.73 Full crystallographic information is available from OCA.
Reference
Cation binding to a Bacillus (1,3-1,4)-beta-glucanase. Geometry, affinity and effect on protein stability., Keitel T, Meldgaard M, Heinemann U, Eur J Biochem. 1994 May 15;222(1):203-14. PMID:8200344
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