Nuclear Magnetic Resonance Investigations: Structure, Function, and Dynamics

• Main Author: Perkins, Thomas Gardner
• Format: Thesis
• Language: English
• Published: 1982
• Subjects: New Zealand; Sperm whale
• Online Access: https://thesis.library.caltech.edu/10900/; https://thesis.library.caltech.edu/10900/1/Perkins_TG_1982.pdf; https://resolver.caltech.edu/CaltechTHESIS:05162018-141617618

PART I Carbon-13 nuclear magnetic resonance (nmr) spectroscopy has been used to investigate the chemical shifts and spin-lattice relaxation times (T 1 ) of 13 CO bound to two derivatives of protoheme IX. The chemical shift is a function of the nature of the ligand trans to the 13 CO and of the solvent. T 1 measurements of the complex 1-methylimidazole-protoheme IX dimethyl ester- 13 CO reveal that Chemical Shift Anisotropy (CSA) is the dominant relaxation mechanism for the heme bound 13 CO. The aniostropy of the chemical shift tensor, Δσ, for the 13 CO was found to be 584 ± 132 ppm. The chemical shifts are compared with those obtained for 13 CO bound to the monomeric hemoglobin from the marine annelid Glycera dibranchiata . PART II Carbon-13 nuclear magnetic resonance (nmr) spectroscopy has been used to reinvestigate the spin-lattice relaxation times (T 1 ) of 13 CO bound to human hemoglobin (HbA) and sperm whale myoglobin. It has been found that the Chemical Shift Anisotropy (CSA) and Dipole-Dipole (D-D) relaxation mechanisms contribute to the observed T 1 for the protein-bound 13 CO. This observation can explain the lack of an observable nuclear Overhauser effect (NOE) for 13 CO bound to HbA. A reanalysis of the previously determined relaxation times indicates that Δσ = 194 ± 37 ppm and r eff = 1.81 ± 0.02 Å for 13 CO bound to HbA. The significance of these results in relation to the postulated nucleophilic base interaction between the distal residue His-E7 and the protein bound CO is also discussed. PART III The spin-lattice relaxation (T 1 ) times for 13 CO bound to New Zealand white rabbit hemoglobin (HbR) and the monomeric hemoglobin from the marine annelid Glycera dibranchiata (Hb-II) have been investigated. It has been found that the anisotropies of the chemical shift tensor, Δσ, in each protein are vastly different. These results support the existence of a nucleophilic interaction between His-E7 and the heme-bound 13 CO in HbR. In addition, the geometry and rate of internal motion for 13 CO bound to HbR ...