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- Title
Structures of Ovine Corticotropin-Releasing Factor and Its Ala32 Mutant as Studied by CD and NMR Techniques.
- Authors
Ryu, Kyoung-Seok; Choi, Byong-Seok; Chi, Seung-Wook; Kim, Seung-Ho; Kim, Hyoungman
- Abstract
The corticotropin-releasing factor (CRF) is a 41-amino acid peptide-amide hormone, which mediates a general stress-response. It has been reported that the substitution of His-32 in the ovine CRF (oCRF) with Ala brings about a 4.5-fold increase in activity [Kornreich et at (1992) J. Med Chem. 35, 1870–76]. Here, we have determined the secondary structure of this Ala-substituted ovine CRF ([Ala32]oCRF) and compare it with that of oCRF using circular dichroism (CD) and NMR techniques in trifluoroethanol (TFE) solution, which is known to stabilize the α-helix formation. In contrast to an earlier report, it was observed the α-helical structure extends to the C-terminus of oCRF. By analyzing the CαH and NH chemical shifts, the properties of local structures of oCRF were elucidated. The oCRF and [Ala32]oCRF have stable α-helical structures in the middle region, regardless of pH and temperature, and the a-helix initiation regions of these peptides are stabilized as the pH is decreased. However, the [Ala32]oCRF has a more stable α-helical structure than oCRF in the vicinity of the substitution region, and it is thought that this is the cause of the increased activity of [Ala32]oCRF.
- Subjects
CORTICOTROPIN releasing hormone; AMINO acids; CIRCULAR dichroism; PROTEINS; PEPTIDES
- Publication
Journal of Biochemistry, 2000, Vol 127, Issue 4, p687
- ISSN
0021-924X
- Publication type
Article
- DOI
10.1093/oxfordjournals.jbchem.a022658