1jca: Difference between revisions
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|PDB= 1jca |SIZE=350|CAPTION= <scene name='initialview01'>1jca</scene>, resolution 2.5Å | |PDB= 1jca |SIZE=350|CAPTION= <scene name='initialview01'>1jca</scene>, resolution 2.5Å | ||
|SITE= | |SITE= | ||
|LIGAND= <scene name='pdbligand=ZN:ZINC ION'>ZN</scene> | |LIGAND= <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene> | ||
|ACTIVITY= | |ACTIVITY= | ||
|GENE= | |GENE= | ||
|DOMAIN= | |||
|RELATEDENTRY=[[1j73|1J73]] | |||
|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1jca FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1jca OCA], [http://www.ebi.ac.uk/pdbsum/1jca PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1jca RCSB]</span> | |||
}} | }} | ||
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==Overview== | ==Overview== | ||
The design of insulin analogues has emphasized stabilization or destabilization of structural elements according to established principles of protein folding. To this end, solvent-exposed side-chains extrinsic to the receptor-binding surface provide convenient sites of modification. An example is provided by an unfavorable helical C-cap (Thr(A8)) whose substitution by favorable amino acids (His(A8) or Arg(A8)) has yielded analogues of improved stability. Remarkably, these analogues also exhibit enhanced activity, suggesting that activity may correlate with stability. Here, we test this hypothesis by substitution of diaminobutyric acid (Dab(A8)), like threonine an amino acid of low helical propensity. The crystal structure of Dab(A8)-insulin is similar to those of native insulin and the related analogue Lys(A8)-insulin. Although no more stable than native insulin, the non-standard analogue is twice as active. Stability and affinity can therefore be uncoupled. To investigate alternative mechanisms by which A8 substitutions enhance activity, multiple substitutions were introduced. Surprisingly, diverse aliphatic, aromatic and polar side-chains enhance receptor binding and biological activity. Because no relationship is observed between activity and helical propensity, we propose that local interactions between the A8 side-chain and an edge of the hormone-receptor interface modulate affinity. Dab(A8)-insulin illustrates the utility of non-standard amino acids in hypothesis-driven protein design. | The design of insulin analogues has emphasized stabilization or destabilization of structural elements according to established principles of protein folding. To this end, solvent-exposed side-chains extrinsic to the receptor-binding surface provide convenient sites of modification. An example is provided by an unfavorable helical C-cap (Thr(A8)) whose substitution by favorable amino acids (His(A8) or Arg(A8)) has yielded analogues of improved stability. Remarkably, these analogues also exhibit enhanced activity, suggesting that activity may correlate with stability. Here, we test this hypothesis by substitution of diaminobutyric acid (Dab(A8)), like threonine an amino acid of low helical propensity. The crystal structure of Dab(A8)-insulin is similar to those of native insulin and the related analogue Lys(A8)-insulin. Although no more stable than native insulin, the non-standard analogue is twice as active. Stability and affinity can therefore be uncoupled. To investigate alternative mechanisms by which A8 substitutions enhance activity, multiple substitutions were introduced. Surprisingly, diverse aliphatic, aromatic and polar side-chains enhance receptor binding and biological activity. Because no relationship is observed between activity and helical propensity, we propose that local interactions between the A8 side-chain and an edge of the hormone-receptor interface modulate affinity. Dab(A8)-insulin illustrates the utility of non-standard amino acids in hypothesis-driven protein design. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Weiss, M A.]] | [[Category: Weiss, M A.]] | ||
[[Category: Zhao, M.]] | [[Category: Zhao, M.]] | ||
[[Category: a8-lysine human insulin]] | [[Category: a8-lysine human insulin]] | ||
[[Category: insulin receptor]] | [[Category: insulin receptor]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 21:31:35 2008'' | ||
Revision as of 21:31, 30 March 2008
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| , resolution 2.5Å | |||||||
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| Related: | 1J73
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Non-standard Design of Unstable Insulin Analogues with Enhanced Activity
OverviewOverview
The design of insulin analogues has emphasized stabilization or destabilization of structural elements according to established principles of protein folding. To this end, solvent-exposed side-chains extrinsic to the receptor-binding surface provide convenient sites of modification. An example is provided by an unfavorable helical C-cap (Thr(A8)) whose substitution by favorable amino acids (His(A8) or Arg(A8)) has yielded analogues of improved stability. Remarkably, these analogues also exhibit enhanced activity, suggesting that activity may correlate with stability. Here, we test this hypothesis by substitution of diaminobutyric acid (Dab(A8)), like threonine an amino acid of low helical propensity. The crystal structure of Dab(A8)-insulin is similar to those of native insulin and the related analogue Lys(A8)-insulin. Although no more stable than native insulin, the non-standard analogue is twice as active. Stability and affinity can therefore be uncoupled. To investigate alternative mechanisms by which A8 substitutions enhance activity, multiple substitutions were introduced. Surprisingly, diverse aliphatic, aromatic and polar side-chains enhance receptor binding and biological activity. Because no relationship is observed between activity and helical propensity, we propose that local interactions between the A8 side-chain and an edge of the hormone-receptor interface modulate affinity. Dab(A8)-insulin illustrates the utility of non-standard amino acids in hypothesis-driven protein design.
About this StructureAbout this Structure
1JCA is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
ReferenceReference
Non-standard insulin design: structure-activity relationships at the periphery of the insulin receptor., Weiss MA, Wan Z, Zhao M, Chu YC, Nakagawa SH, Burke GT, Jia W, Hellmich R, Katsoyannis PG, J Mol Biol. 2002 Jan 11;315(2):103-11. PMID:11779231
Page seeded by OCA on Sun Mar 30 21:31:35 2008