Correlation of tryptophan fluorescence intensity decay parameters with sup 1 H NMR-determined rotamer conformations: (tryptophan sup 2 )oxytocin

Journal Article · Tue Feb 18 00:00:00 EST 1992 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00121a002· OSTI ID:5687744

Ross, J B.A.; Schwartz, G P; Laws, W R ^[1]; Wyssbrod, H R; Porter, R A ^[2]; Michaels, C A ^[3]

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1. Mount Sinai, New York, NY (United States)
2. Univ. of Louisville, KY (United States)
3. Swarthmore Coll., PA (United States)

While the fluorescence decay kinetics of tyrosine model compounds can be explained in terms of heterogeneity derived from the three ground-state {chi}{sup 1} rotamers, a similar correlation has yet to be directly observed for a tryptophan residue. In addition, the asymmetric indole ring might also lead to heterogeneity from {chi}{sup 2} rotations. In this paper, the time-resolved and steady-state fluorescence properties of (tryptophan{sup 2})oxytocin at pH 3 are presented and compared with {sup 1}H NMR results. According to the unrestricted analyses of individual fluorescence decay curves taken as a function of emission wavelength-independent decay constants, only three exponential terms are required. In addition, the preexponential weighting factors (amplitudes) have the same relative relationship (weights) as the {sup 1}H NMR-determined {chi}{sup 1} rotamer populations of the indole side chain. {sup 15}N was used in heteronuclear coupling experiments to confirm the rotamer assignments. Inclusion of a linked function restricting the decay amplitudes to the {chi}{sup 1} rotamer populations in the individual decay curve analyses and in the global analysis confirms this correlation. According to qualitative nuclear Overhauser data, there are two {chi}{sup 2} populations.

• OSTI ID: 5687744
• Journal Information: Biochemistry; (United States), Vol. 31:6; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
OXYTOCIN
NUCLEAR MAGNETIC RESONANCE
TRYPTOPHAN
RESONANCE FLUORESCENCE
ABSORPTION SPECTRA
OVERHAUSER EFFECT
PROTONS
AMINO ACIDS
AROMATICS
AZAARENES
AZOLES
BARYONS
CARBOXYLIC ACIDS
ELEMENTARY PARTICLES
FERMIONS
FLUORESCENCE
HADRONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HORMONES
INDOLES
LUMINESCENCE
MAGNETIC RESONANCE
NUCLEONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PEPTIDE HORMONES
PITUITARY HORMONES
PROTEINS
PYRROLES
RESONANCE
SPECTRA
550201* - Biochemistry- Tracer Techniques