Solution conformation of Bradkinin and certain fragments
A circular dichroism (CD) study of (D-Pro/sup 2/)- and (D-Pro/sup 3/)-bradykinin, selected peptide fragments, and the model compound, N-acetyl-L-phenylalaninamide, support our previous conclusion (Biochemistry 12, 3780, 1973) that the positive 221-nm CD band of bradykinin is a composite of bands due to two chromophores, the 217-nm band characteristics of the Phe residues overlying the 223-nm band of the N-terminal sequence, Arg-Pro-Pro. The results also indicate that the 223-nm band of Arg-Pro-Pro is associated with the configuration of the Pro-Pro sequence, Arg-D-Pro-Pro and Arg-Pro-D-Pro virtually being diastereoisomers. Accordingly, the conformation of Arg-Pro-Pro was probed in further detail. Upon increasing the temperature from about 27 to 65/sup 0/C, Arg-Pro-Pro undergoes a conformational transition characterized by large positive values of ..delta..H/sup 0/ and ..delta..S/sup 0/, which is interpreted to mean that the structure of water and, thus, solute-solvent interactions play a dominant role in determining the conformation of the peptide. /sup 13/C nuclear magnetic resonance spectroscopy indicates that the effect of lowering the pH on the CD of Arg-Pro-Pro is explicable in terms of hydrogen-bond formation between the carboxyl group and Pro/sup 2/ carbonyl oxygen at acid pH with concomitant cis to trans isomerization. (auth)
- Research Organization:
- Univ. of Colorado Medical Center, Denver
- OSTI ID:
- 7196865
- Journal Information:
- Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 15:3; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
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