1k3m
From Proteopedia
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|ACTIVITY= | |ACTIVITY= | ||
|GENE= | |GENE= | ||
| + | |DOMAIN= | ||
| + | |RELATEDENTRY= | ||
| + | |RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1k3m FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1k3m OCA], [http://www.ebi.ac.uk/pdbsum/1k3m PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1k3m RCSB]</span> | ||
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==Overview== | ==Overview== | ||
To investigate the cooperativity of insulin's structure, a cavity-forming substitution was introduced within the hydrophobic core of an engineered monomer. The substitution, Ile(A2)-->Ala in the A1-A8 alpha-helix, does not impair disulfide pairing between chains. In accord with past studies of cavity-forming mutations in globular proteins, a decrement was observed in thermodynamic stability (DeltaDeltaG(u) 0.4-1.2 kcal/mole). Unexpectedly, CD studies indicate an attenuated alpha-helix content, which is assigned by NMR spectroscopy to selective destabilization of the A1-A8 segment. The analog's solution structure is otherwise similar to that of native insulin, including the B chain's supersecondary structure and a major portion of the hydrophobic core. Our results show that (1) a cavity-forming mutation in a globular protein can lead to segmental unfolding, (2) tertiary packing of Ile(A2), a residue of low helical propensity, stabilizes the A1-A8 alpha-helix, and (3) folding of this segment is not required for native disulfide pairing or overall structure. We discuss these results in relation to a hierarchical pathway of protein folding and misfolding. The Ala(A2) analog's low biological activity (0.5% relative to the parent monomer) highlights the importance of the A1-A8 alpha-helix in receptor recognition. | To investigate the cooperativity of insulin's structure, a cavity-forming substitution was introduced within the hydrophobic core of an engineered monomer. The substitution, Ile(A2)-->Ala in the A1-A8 alpha-helix, does not impair disulfide pairing between chains. In accord with past studies of cavity-forming mutations in globular proteins, a decrement was observed in thermodynamic stability (DeltaDeltaG(u) 0.4-1.2 kcal/mole). Unexpectedly, CD studies indicate an attenuated alpha-helix content, which is assigned by NMR spectroscopy to selective destabilization of the A1-A8 segment. The analog's solution structure is otherwise similar to that of native insulin, including the B chain's supersecondary structure and a major portion of the hydrophobic core. Our results show that (1) a cavity-forming mutation in a globular protein can lead to segmental unfolding, (2) tertiary packing of Ile(A2), a residue of low helical propensity, stabilizes the A1-A8 alpha-helix, and (3) folding of this segment is not required for native disulfide pairing or overall structure. We discuss these results in relation to a hierarchical pathway of protein folding and misfolding. The Ala(A2) analog's low biological activity (0.5% relative to the parent monomer) highlights the importance of the A1-A8 alpha-helix in receptor recognition. | ||
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| - | ==Disease== | ||
| - | Known diseases associated with this structure: Diabetes mellitus, rare form OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=176730 176730]], Hyperproinsulinemia, familial OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=176730 176730]], MODY, one form OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=176730 176730]] | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: mutant]] | [[Category: mutant]] | ||
| - | ''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 21:42:54 2008'' |
Revision as of 18:42, 30 March 2008
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
NMR STRUCTURE OF HUMAN INSULIN MUTANT ILE-A2-ALA, HIS-B10-ASP, PRO-B28-LYS, LYS-B29-PRO, 15 STRUCTURES
Overview
To investigate the cooperativity of insulin's structure, a cavity-forming substitution was introduced within the hydrophobic core of an engineered monomer. The substitution, Ile(A2)-->Ala in the A1-A8 alpha-helix, does not impair disulfide pairing between chains. In accord with past studies of cavity-forming mutations in globular proteins, a decrement was observed in thermodynamic stability (DeltaDeltaG(u) 0.4-1.2 kcal/mole). Unexpectedly, CD studies indicate an attenuated alpha-helix content, which is assigned by NMR spectroscopy to selective destabilization of the A1-A8 segment. The analog's solution structure is otherwise similar to that of native insulin, including the B chain's supersecondary structure and a major portion of the hydrophobic core. Our results show that (1) a cavity-forming mutation in a globular protein can lead to segmental unfolding, (2) tertiary packing of Ile(A2), a residue of low helical propensity, stabilizes the A1-A8 alpha-helix, and (3) folding of this segment is not required for native disulfide pairing or overall structure. We discuss these results in relation to a hierarchical pathway of protein folding and misfolding. The Ala(A2) analog's low biological activity (0.5% relative to the parent monomer) highlights the importance of the A1-A8 alpha-helix in receptor recognition.
About this Structure
1K3M is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
A cavity-forming mutation in insulin induces segmental unfolding of a surrounding alpha-helix., Xu B, Hua QX, Nakagawa SH, Jia W, Chu YC, Katsoyannis PG, Weiss MA, Protein Sci. 2002 Jan;11(1):104-16. PMID:11742127
Page seeded by OCA on Sun Mar 30 21:42:54 2008
Categories: Protein complex | Chu, Y C. | Hua, Q X. | Jia, W. | Katsoyannis, P G. | Nakagawa, S H. | Weiss, M A. | Xu, B. | Hormone | Human insulin | Mutant
