Molecular structure, dynamics and hydration studies of soybean storage proteins and model systems by nuclear magnetic resonance

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5614002

Kakalis, L T

The potential of high-resolution {sup 13}C NMR for the characterization of soybean storage proteins was explored. The spectra of a commercial soy protein isolate as well as those of alkali-denatured 7S and 11S soybean globulins were well resolved and tentatively assigned. Relaxation measurements indicated fast motion for several side chains and the protein backbone. Protein fractions (11S and 7S) were also investigated at various states of molecular association. The large size of the multisubunit soybean storage proteins affected adversely both the resolution and the sensitivity of their {sup 13}C NMR spectra. A comparison of {sup 17}O and {sup 2}H NMR relaxation rates of water in solutions of lysozyme (a model system) as a function of concentration, pH and magnetic field suggested that only {sup 17}O monitors directly the hydration of lysozyme. Analysis of {sup 17}O NMR lysozyme hydration data in terms of a two-state, fast-exchange, anisotropic model resulted in hydration parameters which are consistent with the protein's physico-chemical properties. The same model was applied to the calculation of the amount and mobility of bound water in soy protein dispersions by means of {sup 17}O NMR relaxation measurements as a function of protein concentration. The protein concentration dependences of {sup 1}H transverse NMR relaxation measurements at various pH and ionic strength values were fitted by a viral expansion. The interpretation of the data was based on the effects of protein aggregation, salt binding and protein group ionization on the NMR measurements. In all cases, relaxation rates showed a linear dependence on protein activity.

• Research Organization: Illinois Univ., Urbana, IL (USA)
• OSTI ID: 5614002
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
CARBON 13
CARBON ISOTOPES
CHEMICAL PROPERTIES
DEUTERIUM
ENZYMES
EVEN-ODD NUCLEI
FOOD
GLYCOSYL HYDROLASES
HYDRATION
HYDROGEN ISOTOPES
HYDROLASES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LYSOZYME
MAGNETIC RESONANCE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
O-GLYCOSYL HYDROLASES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OXYGEN 17
OXYGEN ISOTOPES
PHYSICAL PROPERTIES
PLANTS
PROTEIN STRUCTURE
PROTEINS
RESONANCE
SOLVATION
SOYBEANS
SPECTRA
STABLE ISOTOPES
TRACER TECHNIQUES
VEGETABLES