1hjs: Difference between revisions
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==Overview== | ==Overview== | ||
beta-1,4-Galactanases hydrolyze the galactan side chains that are part of, the complex carbohydrate structure of the pectin. They are assigned to, family 53 of the glycoside hydrolases and display significant variations, in their pH and temperature optimum and stability. Two fungal, beta-1,4-galactanases from Myceliophthora thermophila and Humicola, insolens have been cloned and heterologously expressed, and the crystal, structures of the gene products were determined. The structures are, compared to the previously only known family 53 structure of the, galactanase from Aspergillus aculeatus (AAGAL) showing approximately 56%, identity. The M. thermophila and H. insolens galactanases are thermophilic, enzymes and are most active at neutral to basic pH, whereas AAGAL is, mesophilic and most ... | beta-1,4-Galactanases hydrolyze the galactan side chains that are part of, the complex carbohydrate structure of the pectin. They are assigned to, family 53 of the glycoside hydrolases and display significant variations, in their pH and temperature optimum and stability. Two fungal, beta-1,4-galactanases from Myceliophthora thermophila and Humicola, insolens have been cloned and heterologously expressed, and the crystal, structures of the gene products were determined. The structures are, compared to the previously only known family 53 structure of the, galactanase from Aspergillus aculeatus (AAGAL) showing approximately 56%, identity. The M. thermophila and H. insolens galactanases are thermophilic, enzymes and are most active at neutral to basic pH, whereas AAGAL is, mesophilic and most active at acidic pH. The structure of the M., thermophila galactanase (MTGAL) was determined from crystals obtained with, HEPES and TRIS buffers to 1.88 A and 2.14 A resolution, respectively. The, structure of the H. insolens galactanase (HIGAL) was determined to 2.55 A, resolution. The thermostability of MTGAL and HIGAL correlates with, increase in the protein rigidity and electrostatic interactions, stabilization of the alpha-helices, and a tighter packing. An inspection, of the active sites in the three enzymes identifies several amino acid, substitutions that could explain the variation in pH optimum. Examination, of the activity as a function of pH for the D182N mutant of AAGAL and the, A90S/ H91D mutant of MTGAL showed that the difference in pH optimum, between AAGAL and MTGAL is at least partially associated with differences, in the nature of residues at positions 182, 90, and/or 91. | ||
==About this Structure== | ==About this Structure== | ||
1HJS is a | 1HJS is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Corynascus_heterothallicus Corynascus heterothallicus] with NAG, SO4, EPE and PEG as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Arabinogalactan_endo-1,4-beta-galactosidase Arabinogalactan endo-1,4-beta-galactosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.89 3.2.1.89] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1HJS OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: thermostability]] | [[Category: thermostability]] | ||
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Revision as of 14:59, 5 November 2007
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STRUCTURE OF TWO FUNGAL BETA-1,4-GALACTANASES: SEARCHING FOR THE BASIS FOR TEMPERATURE AND PH OPTIMUM.
OverviewOverview
beta-1,4-Galactanases hydrolyze the galactan side chains that are part of, the complex carbohydrate structure of the pectin. They are assigned to, family 53 of the glycoside hydrolases and display significant variations, in their pH and temperature optimum and stability. Two fungal, beta-1,4-galactanases from Myceliophthora thermophila and Humicola, insolens have been cloned and heterologously expressed, and the crystal, structures of the gene products were determined. The structures are, compared to the previously only known family 53 structure of the, galactanase from Aspergillus aculeatus (AAGAL) showing approximately 56%, identity. The M. thermophila and H. insolens galactanases are thermophilic, enzymes and are most active at neutral to basic pH, whereas AAGAL is, mesophilic and most active at acidic pH. The structure of the M., thermophila galactanase (MTGAL) was determined from crystals obtained with, HEPES and TRIS buffers to 1.88 A and 2.14 A resolution, respectively. The, structure of the H. insolens galactanase (HIGAL) was determined to 2.55 A, resolution. The thermostability of MTGAL and HIGAL correlates with, increase in the protein rigidity and electrostatic interactions, stabilization of the alpha-helices, and a tighter packing. An inspection, of the active sites in the three enzymes identifies several amino acid, substitutions that could explain the variation in pH optimum. Examination, of the activity as a function of pH for the D182N mutant of AAGAL and the, A90S/ H91D mutant of MTGAL showed that the difference in pH optimum, between AAGAL and MTGAL is at least partially associated with differences, in the nature of residues at positions 182, 90, and/or 91.
About this StructureAbout this Structure
1HJS is a Single protein structure of sequence from Corynascus heterothallicus with NAG, SO4, EPE and PEG as ligands. Active as Arabinogalactan endo-1,4-beta-galactosidase, with EC number 3.2.1.89 Structure known Active Site: AC1. Full crystallographic information is available from OCA.
ReferenceReference
Structure of two fungal beta-1,4-galactanases: searching for the basis for temperature and pH optimum., Le Nours J, Ryttersgaard C, Lo Leggio L, Ostergaard PR, Borchert TV, Christensen LL, Larsen S, Protein Sci. 2003 Jun;12(6):1195-204. PMID:12761390
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Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)
OCA- Pages with broken file links
- Arabinogalactan endo-1,4-beta-galactosidase
- Corynascus heterothallicus
- Single protein
- Borchert, T.V.
- Christensen, L.L.H.
- Larsen, S.
- Leggio, L.Lo.
- Nours, J.Le.
- Ostergaard, P.R.
- Ryttersgaard, C.
- EPE
- NAG
- PEG
- SO4
- 4-galactanases
- Alkalophile
- Beta-1
- Clan gh-a
- Family 53 glycoside hydrolase
- Hydrolase
- Ph optimum
- Thermophile
- Thermostability