1hjs: Difference between revisions

Revision as of 18:55, 2 May 2008

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. 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 Page seeded by OCA on Fri May 2 18:55:08 2008

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA

@@ Line 1: / Line 1: @@
 [[Image:1hjs.gif|left|200px]]
- {{Structure
+<!--
-|PDB= 1hjs |SIZE=350|CAPTION= <scene name='initialview01'>1hjs</scene>, resolution 1.87&Aring;
+The line below this paragraph, containing "STRUCTURE_1hjs", creates the "Structure Box" on the page.
-|SITE= <scene name='pdbsite=AC1:Peg+Binding+Site+For+Chain+D'>AC1</scene>
+You may change the PDB parameter (which sets the PDB file loaded into the applet)
-|LIGAND= <scene name='pdbligand=EPE:4-(2-HYDROXYETHYL)-1-PIPERAZINE+ETHANESULFONIC+ACID'>EPE</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=PEG:DI(HYDROXYETHYL)ETHER'>PEG</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene>
+or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
-|ACTIVITY= <span class='plainlinks'>[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] </span>
+or leave the SCENE parameter empty for the default display.
-|GENE=
+-->
-|DOMAIN=
+{{STRUCTURE_1hjs|  PDB=1hjs  |  SCENE=  }}
-|RELATEDENTRY=
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1hjs FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1hjs OCA], [http://www.ebi.ac.uk/pdbsum/1hjs PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1hjs RCSB]</span>
-}}
 '''STRUCTURE OF TWO FUNGAL BETA-1,4-GALACTANASES: SEARCHING FOR THE BASIS FOR TEMPERATURE AND PH OPTIMUM.'''
@@ Line 34: / Line 31: @@
 [[Category: Ryttersgaard, C.]]
 [[Category: 4-galactanase]]
-[[Category: alkalophile]]
+[[Category: Alkalophile]]
-[[Category: beta-1]]
+[[Category: Beta-1]]
-[[Category: clan gh-a]]
+[[Category: Clan gh-a]]
-[[Category: family 53 glycoside hydrolase]]
+[[Category: Family 53 glycoside hydrolase]]
-[[Category: hydrolase]]
+[[Category: Hydrolase]]
-[[Category: ph optimum]]
+[[Category: Ph optimum]]
-[[Category: thermophile]]
+[[Category: Thermophile]]
-[[Category: thermostability]]
+[[Category: Thermostability]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May  2 18:55:08 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 21:06:14 2008''