Origin and Behavior of Deuteron Spin Echoes in Selectively Labeled Amino Acids, Myoglobin Microcrystals, and Purple Membranes?

• Main Authors: Ion C Baianu, H S Gutowsky, Eric Oldfield
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1984
• Subjects: Boden; Catodon; Sperm whale
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1083.822; http://feh.scs.uiuc.edu/doc/papers/1201228224_79.pdf

ABSTRACT: We have obtained deuterium NMR spin-echo spectra of crystalline ~-[ y -~H~] v a l i n e , [S-methyl-*H3]-methionine, cyanoferrimyoglobin from sperm whale (Physeter catodon), containing deuteriomethyl groups at methionine-55 and methionine-1 3 1, and [y-2H6]valine-labeled bacteriorhodopsin in the purple membrane of Halobacterium halobium R1. By using 90-~-&,~ (XU) and 90-rfloe (XX) pulse sequences and observing the dependence of the spin-echo amplitude upon the interpulse spacing T , we have determined that the so-called "quadrupole echoes" obtained in these typical selectively deuterated condensed-phase biological systems are in fact strongly modulated by proton-deuteron and deuteron-deuteron dipolar interactions. The two amino acids and the protein crystals behaved as typical organic solids, with no F o r over 10 years now, there has been considerable interest in the use of deuterium (*H) nuclear magnetic resonance (NMR)' as a tool for probing the static and dynamic structures of cell membranes Many groups are now using 2H NMR of selectively 2H-labeled compounds to study the static and dynamic structures of various biological systems Theory NMR spin echoes from a quadrupolar nucleus in a solid were first observed and calculated by Subsequently, however, deuterium NMR spin echoes were observed for such a 90-7-floo sequence (Boden et al., 1978), when / 3 # k X 90° and k = 0, 1,2, . the observation of spin echoes with a 9O-r-flo0 sequence in perdeuterated organic solids proves that dipolar interactions between deuterons, at least in these systems, cannot be neglected since such echoes arise only when dipolar interactions are present