/sup 13/C and /sup 1/H nuclear magnetic resonance studies of bradykinin and selected peptide fragments
Complete /sup 13/C chemical shift assignments of the nonapeptide bradykinin have been made on the basis of pH titration studies and the examination of peptide fragments. Hysteresis effects previously reported for the /sup 13/C shifts of the Arg/sup 9/ resonances as a function of pH and interpreted to reflect an intramolecular salt bridge involving the Arg/sup 1/ guanido and the Arg/sup 9/ carboxyl (Ivanov, V. T., et al. (1975) Bioorg. Khim. 1, 1241; Proc. 4th Am. Pept. Symp., 151) were not observed in the present study. Chemical shifts of the proline carbons indicate that the trans configuration about the three X-Pro peptide bonds is strongly favored in all cases, although the minor cis resonances accounting for approximately 10% of the proline intensity can also be observed. In addition, there appears to be no significant pH sensitivity of the cis reversible trans equilibria. Studies of the solvent dependence (water ..-->.. methanol) of the carbonyl shifts are consistent with the possibility of an intramolecular hydrogen bond involving the Ser/sup 6/ carbonyl oxygen. Preliminary /sup 1/H nuclear magnetic resonance studies of the amide proton region of bradykinin and the C-terminal tetrapeptide Ser-Pro-Phe-Arg are also reported. In the latter peptide, the Phe/sup 8/ and Arg/sup 9/ amide proton resonances appear as two sets of resonances corresponding to the cis and trans configurations of the Ser-Pro bond. The temperature dependenceof the proton shifts of the amide resonances is independent of whether the Ser-Pro bond is cis or trans, indicating that any intramolecular hydrogen bonding existing only for the trans peptide is insufficient to significantly reduce this parameter. Measurements of the /sup 13/C spin-lattice relaxation times indicate rapid internal motion for all of the peptide side chains, supporting the interpretation that bradykinin exists in solution primarily in a disordered state.
- Research Organization:
- Los Alamos Scientific Lab., NM
- OSTI ID:
- 6744087
- Journal Information:
- Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 17:12; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400103 -- Radiometric & Radiochemical Procedures-- (-1987)
550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
BARYONS
BRADYKININ
CARBON 13
CARBON ISOTOPES
CHEMICAL SHIFT
CONFIGURATION INTERACTION
ELEMENTARY PARTICLES
EVEN-ODD NUCLEI
FERMIONS
HADRONS
ISOTOPES
KININS
LIGHT NUCLEI
MAGNETIC RESONANCE
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUCLEONS
ORGANIC COMPOUNDS
PEPTIDES
PROTEINS
PROTONS
RELAXATION
RESONANCE
SPIN-LATTICE RELAXATION
STABLE ISOTOPES
STRUCTURAL CHEMICAL ANALYSIS