In a preliminary report, we have previously shown that N-[(2,2,5,5-tetramethyl-1-oxypyrrolidin-3-yl)carbonyl]-L-phenyl ala nine tert-butyl ester (SL-Phe) exhibits specific binding to hemoglobin and an antiaggregation activity more than 2 orders of magnitude greater than that of phenylalanine [Lu, H.-Z., Currie, B. L., & Johnson, M. E. (1984) FEBS Lett. 173, 259-263]. Transverse 1H NMR relaxation measurements have been used to investigate the interaction of SL-Phe with hemoglobin molecules by use of the resonances assigned to the C2 protons of the beta 2 His, the beta 143 His, and the beta 146 or beta 97 His residues as intrinsic probes. Distance calculations using the paramagnetically induced relaxation data suggest that the SL-Phe binding site is approximately 12-16 A away from the C2 protons of the beta 2 His and the beta 146 or beta 97 His residues in the (carbonmonoxy)hemoglobin tetramer; for deoxyhemoglobin, the distances are approximately 14-17 A between the SL-Phe binding site and the C2 protons of the beta 2 His, the beta 143 His, and the beta 146 His residues. Calculations using the (carbonmonoxy)hemoglobin crystal atomic coordinates only restrict the probable SL-Phe binding region to the full F and H helices of the beta-chain and a small section of the alpha-chain. For deoxyhemoglobin, the distance calculations provide greater restrictions on the probable binding region, limiting it to small sections of the beta-chain F, G, and H helices near the EF bend and to a few residues on the alpha-chain.(ABSTRACT TRUNCATED AT 250 WORDS)
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.