Nuclear magnetic resonance studies of hemoproteins. III. Restricted rotation of a heme side chain methyl group in some ferric myoglobin complexes and its implication in van der Waals contact in the heme side chain environments

1974 ◽  
Vol 96 (23) ◽  
pp. 7365-7367 ◽  
Author(s):  
Isao Morishima ◽  
Tetsutaro Iizuka
1968 ◽  
Vol 46 (17) ◽  
pp. 2827-2833 ◽  
Author(s):  
Y. L. Chow ◽  
C. J. Colón

The nuclear magnetic resonance spectra of various heterocyclic nitrosamines were studied in solution. A qualitative view of the long-range diamagnetic effects of a nitrosamino group is advanced and correlated with the chemical shifts of α-equatorial protons and the methyl group in those nitrosamines possessing a preferred conformation or a rigid system. The use of this correlation to decide the configuration and conformation of heterocyclic nitrosamines is discussed. A large chemical shift difference (ca. 3 p.p.m.) between a cis α-axial and a cis α-equatorial proton was noted.


2001 ◽  
Vol 67 (3) ◽  
pp. 1030-1034 ◽  
Author(s):  
Francesc X. Prenafeta-Boldú ◽  
Dion M. A. M. Luykx ◽  
Jacques Vervoort ◽  
Jan A. M. de Bont

ABSTRACT We used isomeric fluorotoluenes as model substrates to study the catabolism of toluene by five deuteromycete fungi and one ascomycete fungus capable of growth on toluene as the sole carbon and energy source, as well as by two fungi (Cunninghamella echinulata and Aspergillus niger) that cometabolize toluene. Whole cells were incubated with 2-, 3-, and 4-fluorotoluene, and metabolites were characterized by 19F nuclear magnetic resonance. Oxidation of fluorotoluene by C. echinulata was initiated either at the aromatic ring, resulting in fluorinated o-cresol, or at the methyl group to form fluorobenzoate. The initial conversion of the fluorotoluenes by toluene-grown fungi occurred only at the side chain and resulted in fluorinated benzoates. The latter compounds were the substrate for the ring hydroxylation and, depending on the fluorine position, were further metabolized up to catecholic intermediates. From the19F nuclear magnetic resonance metabolic profiles, we propose that diverse fungi that grow on toluene assimilate toluene by an initial oxidation of the methyl group.


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