1o8m
From Proteopedia
(New page: 200px<br /><applet load="1o8m" size="450" color="white" frame="true" align="right" spinBox="true" caption="1o8m, resolution 2.20Å" /> '''PECTATE LYASE C FROM...) |
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| - | [[Image:1o8m.jpg|left|200px]]<br /><applet load="1o8m" size=" | + | [[Image:1o8m.jpg|left|200px]]<br /><applet load="1o8m" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1o8m, resolution 2.20Å" /> | caption="1o8m, resolution 2.20Å" /> | ||
'''PECTATE LYASE C FROM ERWINIA CHRYSANTHEMI AT PH 4.5 WITH NO CA2+ ADDED'''<br /> | '''PECTATE LYASE C FROM ERWINIA CHRYSANTHEMI AT PH 4.5 WITH NO CA2+ ADDED'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Ca(2+) is essential for in vitro activity of Erwinia chrysanthemi pectate | + | Ca(2+) is essential for in vitro activity of Erwinia chrysanthemi pectate lyase C (PelC). Crystallographic analyses of 11 PelC-Ca(2+) complexes, formed at pH 4.5, 9.5, and 11.2 under varying Ca(2+) concentrations, have been solved and refined at a resolution of 2.2 A. The Ca(2+) site represents a new motif for Ca(2+), consisting primarily of beta-turns and beta-strands. The principal differences between PelC and the PelC-Ca(2+) structures at all pH values are the side-chain conformations of Asp-129 and Glu-166 as well as the occupancies of four water molecules. According to calculations of pK(a) values, the presence of Ca(2+) and associated structural changes lower the pK(a) of Arg-218, the amino acid responsible for proton abstraction during catalysis. The Ca(2+) affinity for PelC is weak, as the K(d) was estimated to be 0.132 (+/-0.004) mm at pH 9.5, 1.09 (+/-0.29) mm at pH 11.2, and 5.84 (+/-0.41) mm at pH 4.5 from x-ray diffraction studies and 0.133 (+/-0.045) mm at pH 9.5 from intrinsic tryptophan fluorescence measurements. Given the pH dependence of Ca(2+) affinity, PelC activity at pH 4.5 has been reexamined. At saturating Ca(2+) concentrations, PelC activity increases 10-fold at pH 4.5 but is less than 1% of maximal activity at pH 9.5. Taken together, the studies suggest that the primary Ca(2+) ion in PelC has multiple functions. |
==About this Structure== | ==About this Structure== | ||
| - | 1O8M is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Erwinia_chrysanthemi Erwinia chrysanthemi]. Active as [http://en.wikipedia.org/wiki/Pectate_lyase Pectate lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.2.2 4.2.2.2] Full crystallographic information is available from [http:// | + | 1O8M is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Erwinia_chrysanthemi Erwinia chrysanthemi]. Active as [http://en.wikipedia.org/wiki/Pectate_lyase Pectate lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.2.2 4.2.2.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1O8M OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Pectate lyase]] | [[Category: Pectate lyase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Herron, S | + | [[Category: Herron, S R.]] |
| - | [[Category: Jurnak, F | + | [[Category: Jurnak, F A.]] |
[[Category: calcium binding]] | [[Category: calcium binding]] | ||
[[Category: lyase]] | [[Category: lyase]] | ||
| Line 21: | Line 21: | ||
[[Category: pectate lyase cleavage]] | [[Category: pectate lyase cleavage]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:14:41 2008'' |
Revision as of 12:14, 21 February 2008
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PECTATE LYASE C FROM ERWINIA CHRYSANTHEMI AT PH 4.5 WITH NO CA2+ ADDED
Overview
Ca(2+) is essential for in vitro activity of Erwinia chrysanthemi pectate lyase C (PelC). Crystallographic analyses of 11 PelC-Ca(2+) complexes, formed at pH 4.5, 9.5, and 11.2 under varying Ca(2+) concentrations, have been solved and refined at a resolution of 2.2 A. The Ca(2+) site represents a new motif for Ca(2+), consisting primarily of beta-turns and beta-strands. The principal differences between PelC and the PelC-Ca(2+) structures at all pH values are the side-chain conformations of Asp-129 and Glu-166 as well as the occupancies of four water molecules. According to calculations of pK(a) values, the presence of Ca(2+) and associated structural changes lower the pK(a) of Arg-218, the amino acid responsible for proton abstraction during catalysis. The Ca(2+) affinity for PelC is weak, as the K(d) was estimated to be 0.132 (+/-0.004) mm at pH 9.5, 1.09 (+/-0.29) mm at pH 11.2, and 5.84 (+/-0.41) mm at pH 4.5 from x-ray diffraction studies and 0.133 (+/-0.045) mm at pH 9.5 from intrinsic tryptophan fluorescence measurements. Given the pH dependence of Ca(2+) affinity, PelC activity at pH 4.5 has been reexamined. At saturating Ca(2+) concentrations, PelC activity increases 10-fold at pH 4.5 but is less than 1% of maximal activity at pH 9.5. Taken together, the studies suggest that the primary Ca(2+) ion in PelC has multiple functions.
About this Structure
1O8M is a Single protein structure of sequence from Erwinia chrysanthemi. Active as Pectate lyase, with EC number 4.2.2.2 Full crystallographic information is available from OCA.
Reference
Characterization and implications of Ca2+ binding to pectate lyase C., Herron SR, Scavetta RD, Garrett M, Legner M, Jurnak F, J Biol Chem. 2003 Apr 4;278(14):12271-7. Epub 2003 Jan 22. PMID:12540845
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