Selenium-77 nuclear magnetic resonance studies of various biological systems

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

OSTI ID:5671447

Chanson, R S

Selenium-77 nuclear magnetic resonance spectroscopy has been used as a valuable technique for the investigation of various biological systems. Several para-substituted phenyl(selenyl) acetates were studied as inhibitors of the serine protease, {alpha}-chymotrypsin, and the results showed that a downfield shift ({minus}15.6 to {minus}53.3 ppm) in the selenium resonance occurred upon the binding of the inhibitor to the enzyme. The {Delta} values determined for these inhibitors are much greater than those values previously determined for similar inhibitors with proton, carbon-13 and fluorine-19 NMR spectroscopy. In past studies, the largest chemical shifts (3-7 ppm) have come from investigations with the fluorine-19 nucleus. The results from these selenium-77 NMR studies clearly show the sensitivity of this multinuclear technique and firmly establishes selenium-77 NMR spectroscopy as a valuable method for investigating the binding of substrates and inhibitors to enzymes. Phenyl isothiocyanate or Edman's reagent has been the compound of choice for determining the amino acid sequence of peptide fragments. The use of p-tolyl isoselenocyanate as a selenium-containing analog of Edman's reagent was investigated and followed very readily by {sup 77}Se NMR spectroscopy. In each of the three steps involved in the degradation process, the intermediates were characterized by several analytical techniques and multinuclear NMR spectroscopy. These studies demonstrate that p-tolyl isoselenocyanate follows a similar pathway during the degradation process, but the conditions required in each step are milder than those required for the sulfur compound. The results from the {sup 77}Se NMR studies also show that the selenium nucleus can differentiate between varying substituents up to six bonds removed from the selenium moiety.

• Research Organization: South Carolina Univ., Columbia, SC (United States)
• OSTI ID: 5671447
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACID SEQUENCE
CHEMICAL SHIFT
ENZYME INHIBITORS
ENZYMES
EVEN-ODD NUCLEI
HYDROLASES
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAGNETIC RESONANCE
MOLECULAR STRUCTURE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
PEPTIDE HYDROLASES
RADIOISOTOPES
REAGENTS
RESONANCE
SECONDS LIVING RADIOISOTOPES
SELENIUM 77
SELENIUM ISOTOPES
SPECTRA
STABLE ISOTOPES
TRACER TECHNIQUES