1nkf
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CALCIUM-BINDING PEPTIDE, NMR, 30 STRUCTURES
OverviewOverview
A 12-residue peptide AcDKDGDGYISAAENH2 analogous to the third, calcium-binding loop of calmodulin strongly coordinates lanthanide ions (K, = 10(5) M-1). When metal saturated, the peptide adopts a very rigid, structure, the same as in the native protein, with three last residues AAE, fixed in the alpha-helical conformation. Therefore, the peptide provides, an ideal helix nucleation site for peptide segments attached to its C, terminus. NMR and CD investigations of peptide AcDKDGDGYISAAEAAAQNH2, presented in this paper show that residues A13-Q16 form an alpha-helix of, very high stability when the La3+ ion is bound to the D1-E12 loop. In, fact, the lowest estimates of the helix content in this segment give, values of at least 80% at 1 degreesC and 70% at 25 degreesC. This finding, is not compatible with existing helix-coil transition theories and helix, propagation parameters, s, reported in the literature. We conclude, therefore, that the initial steps of helix propagation are characterized, by much larger s values, whereas helix nucleation is even more unfavorable, than is believed. In light of our findings, thermodynamics of the nascent, alpha-helices is discussed. The problem of CD spectra of very short, alpha-helices is also addressed.
DiseaseDisease
Known diseases associated with this structure: Cavernous malformations of CNS and retina OMIM:[604214], Cerebral cavernous malformations-1 OMIM:[604214], Hyperkeratotic cutaneous capillary-venous malformations associated with cerebral capillary malformations OMIM:[604214], Leukemia, acute T-cell lymphoblastic OMIM:[603025], Leukemia, acute myeloid OMIM:[603025]
About this StructureAbout this Structure
1NKF is a Single protein structure of sequence from Homo sapiens with ACE, NH2 and LA as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Alpha-helix nucleation by a calcium-binding peptide loop., Siedlecka M, Goch G, Ejchart A, Sticht H, Bierzyski A, Proc Natl Acad Sci U S A. 1999 Feb 2;96(3):903-8. PMID:9927666
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