/sup 13/C nuclear magnetic resonance study of the cis-trans isomerism in X-Pro-Pro tripeptides
/sup 13/C nuclear magnetic resonance has been used to characterize quantitatively the cis-trans isomerism about both peptide bonds in the tripeptides Ser-Pro-Pro and Arg-Pro-Pro. Detailed pH titration data indicate that the configuration about both peptide bonds is closely linked to titration of the terminal carboxyl group and, to a lesser extent, to titration of the terminal amino group. The Pro/sup 2/ C-3 resonance has been found particularly useful for interpretation due to its sensitivity to the isomerization about both peptide bonds. Analysis of the probabilities of the trans-trans, cis-cis, cis-trans, and trans-cis isomers in aqueous solution indicates a stability decrease in the order given. Similarities in the isomerization behavior of the two peptides indicate that side chain interactions involving the first residue have very little effect on the observed cis/trans ratios. The sensitivity of the cis/trans ratio to titration of the terminal amino group is most readily explained on the basis of an indirect effect on carbonyl-carbonyl repulsion.
- Research Organization:
- Los Alamos Scientific Lab., NM
- OSTI ID:
- 6725889
- 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
AQUEOUS SOLUTIONS
CARBON 13
CARBON ISOTOPES
CONFIGURATION INTERACTION
DISPERSIONS
EVEN-ODD NUCLEI
ISOMER SHIFT
ISOMERS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MIXTURES
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC COMPOUNDS
PEPTIDES
PROTEINS
RESONANCE
SOLUTIONS
STABILITY
STABLE ISOTOPES
STRUCTURAL CHEMICAL ANALYSIS