MOSSBAUER AND EPR STUDY OF NITROSYL HEMOGLOBIN

consist of a superposition of spectra from high- and few-spin Fe(III), deoxygenated hemoglobin and a component corresponding to S = 1/2, g = 2, hyperfine constants A,Ig,P, A,Ig,P, -19.6Nitrosyl hemoglobin was p repared by bubbling fresh Fe-57-enriched rat hemoglobin with NO. S- an d X-band EPR spectra at 77 K are typical for an S = 1/2 system with an anisotropic g-tensor and exhibit hyperfine interactions of N-14 with the electronic spin. Mossbauer spectra at 4.2 and 100 K consist of a s uperposition of spectra from high- and low-spin Fe(III), deoxygenated hemoglobin and a component corresponding to S = 1/2, g = 2, hyperfine constants A(xx)/g(n) beta(n) = A(yy)/g(n) beta(n) = -19.6 T, A(zz)/g(n ) beta(n) = 6.8 T, quadrupole splitting Delta E(Q) = 1.5 mm s(-1), iso mer shift I-s = 0.42 mm s(-1) and linewidth 0.4 mm s(-1). The spin-lat tice relaxation rate at 100 K is <2 x 10(6) s(-1).