1fn0: Difference between revisions
New page: left|200px<br /><applet load="1fn0" size="450" color="white" frame="true" align="right" spinBox="true" caption="1fn0, resolution 2.00Å" /> '''STRUCTURE OF A MUTAN... |
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[[Image:1fn0.jpg|left|200px]]<br /><applet load="1fn0" size=" | [[Image:1fn0.jpg|left|200px]]<br /><applet load="1fn0" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1fn0, resolution 2.00Å" /> | caption="1fn0, resolution 2.00Å" /> | ||
'''STRUCTURE OF A MUTANT WINGED BEAN CHYMOTRYPSIN INHIBITOR PROTEIN, N14D.'''<br /> | '''STRUCTURE OF A MUTANT WINGED BEAN CHYMOTRYPSIN INHIBITOR PROTEIN, N14D.'''<br /> | ||
==Overview== | ==Overview== | ||
A double-headed chymotrypsin inhibitor, WCI, from winged bean seeds was | A double-headed chymotrypsin inhibitor, WCI, from winged bean seeds was cloned for structural and biochemical studies. The inhibitor was subjected to two point mutations at a conserved position, Asn14. This residue, known to have a pivotal role in stabilizing the first reactive-site loop (Gln63-Phe68) of the inhibitor, is highly conserved in the sequences of the other members of Kunitz (STI) family as well as in the sequences of Kazal family of serine protease inhibitors. The mutants, N14K and N14D, were subjected to biochemical assay and their characteristics were compared with those of the recombinant inhibitor (rWCI). Crystallographic studies of the recombinant and the mutant proteins are discussed. These studies were primarily aimed at understanding the importance of the protein scaffolding towards the conformational rigidity of the reactive-site loop. Our analysis reveals that, as the Lys14 side chain takes an unusual fold in N14K and the Asp14 side chain in N14D interacts with the loop residues by water-mediated hydrogen bonds, the canonical conformation of the loop has remained effectively intact in both the mutant structures. However, minor alterations such as a 2-fold increase in the inhibitory affinity towards the cognate enzyme were observed. | ||
==About this Structure== | ==About this Structure== | ||
1FN0 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Psophocarpus_tetragonolobus Psophocarpus tetragonolobus] with SO4 as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | 1FN0 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Psophocarpus_tetragonolobus Psophocarpus tetragonolobus] with <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FN0 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Chakrabarti, C.]] | [[Category: Chakrabarti, C.]] | ||
[[Category: Dasgupta, J.]] | [[Category: Dasgupta, J.]] | ||
[[Category: Dattagupta, J | [[Category: Dattagupta, J K.]] | ||
[[Category: Ghosh, S.]] | [[Category: Ghosh, S.]] | ||
[[Category: Ravichandran, S.]] | [[Category: Ravichandran, S.]] | ||
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[[Category: beta trefoil]] | [[Category: beta trefoil]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:40:22 2008'' | ||
Revision as of 13:40, 21 February 2008
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STRUCTURE OF A MUTANT WINGED BEAN CHYMOTRYPSIN INHIBITOR PROTEIN, N14D.
OverviewOverview
A double-headed chymotrypsin inhibitor, WCI, from winged bean seeds was cloned for structural and biochemical studies. The inhibitor was subjected to two point mutations at a conserved position, Asn14. This residue, known to have a pivotal role in stabilizing the first reactive-site loop (Gln63-Phe68) of the inhibitor, is highly conserved in the sequences of the other members of Kunitz (STI) family as well as in the sequences of Kazal family of serine protease inhibitors. The mutants, N14K and N14D, were subjected to biochemical assay and their characteristics were compared with those of the recombinant inhibitor (rWCI). Crystallographic studies of the recombinant and the mutant proteins are discussed. These studies were primarily aimed at understanding the importance of the protein scaffolding towards the conformational rigidity of the reactive-site loop. Our analysis reveals that, as the Lys14 side chain takes an unusual fold in N14K and the Asp14 side chain in N14D interacts with the loop residues by water-mediated hydrogen bonds, the canonical conformation of the loop has remained effectively intact in both the mutant structures. However, minor alterations such as a 2-fold increase in the inhibitory affinity towards the cognate enzyme were observed.
About this StructureAbout this Structure
1FN0 is a Single protein structure of sequence from Psophocarpus tetragonolobus with as ligand. Full crystallographic information is available from OCA.
ReferenceReference
The role of Asn14 in the stability and conformation of the reactive-site loop of winged bean chymotrypsin inhibitor: crystal structures of two point mutants Asn14-->Lys and Asn14-->Asp., Ravichandran S, Dasgupta J, Chakrabarti C, Ghosh S, Singh M, Dattagupta JK, Protein Eng. 2001 May;14(5):349-57. PMID:11438758
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