Abstract
Human normal adult hemoglobin (Hb A) is a tetrameric protein molecule of ~64 kDa consisting of two identical -chains and two identical -chains of 141 and 146 amino acid residues each and four bound heme moieties. In the oxygen-free form of Hb A, also known as deoxyhemoglobin A (deoxy-Hb A), the hemes are paramagnetic with S = 2. We have measured the one-bond spin-spin couplings (1JNH + 1DNH) on (15N,2H)-labeled deoxy-Hb A in solution as a function of magnetic field strengths from 11.7 to 21.1 T and found that these couplings are linearly proportional to the square of the magnetic field. This field dependence provides an opportunity to extract the residual dipolar couplings (RDCs, 1DNH) and, thus, to compare predictions about the solution structure of deoxy-Hb A to crystal structures for this molecule. Such comparison is essential for our understanding of the structure, dynamics, and function of this allosteric protein under conditions close to the physiological state. This report illustrates the usefulness of using the magnetic-field dependent RDCs to determine the solution structure of a large paramagnetic protein. This method is especially valuable for those proteins whose structures must be determined in an oxygen-free environment.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
