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| [[Image:1glh.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1glh| PDB=1glh | SCENE= }} | | {{STRUCTURE_1glh| PDB=1glh | SCENE= }} |
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| '''CATION BINDING TO A BACILLUS (1,3-1,4)-BETA-GLUCANASE. GEOMETRY, AFFINITY AND EFFECT ON PROTEIN STABILITY'''
| | ===CATION BINDING TO A BACILLUS (1,3-1,4)-BETA-GLUCANASE. GEOMETRY, AFFINITY AND EFFECT ON PROTEIN STABILITY=== |
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| ==Overview==
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| 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. | | The line below this paragraph, {{ABSTRACT_PUBMED_8200344}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 8200344 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_8200344}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Keitel, T.]] | | [[Category: Keitel, T.]] |
| [[Category: Hydrolase]] | | [[Category: Hydrolase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 17:43:35 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 05:28:57 2008'' |
