Magnetic properties of tunicate blood cells. II. Ascidia ceratodes.

The magnetic properties of intact blood cells of the tunicate Ascidia ceratodes have been measured up to 50 kOe with a SQUID susceptometer. Analysis of total metal contents by plasma emission spectroscopy and V(IV) content by epr indicates that approximately 5% of the accumulated vanadium is +4 vanadyl ion. Measured values of the magnetic moment Mp at different values of the applied magnetic field H over the temperature range T = 2-100 K depend on the magnitude of the field indicating magnetic anisotropy of the ground state.

Magnetic properties of tunicate blood cells. I. Ascidia nigra.

The magnetic properties of intact and freeze-dried blood cells of the tunicate Ascidia nigra and of model vanadium(III) and (IV) compounds as polycrystalline solids and in aqueous solution have been measured up to 50 kOe with a SQUID susceptometer. Corrections for the samples' diamagnetism were extracted from the temperature dependence of the data without any further assumptions. For vanadium(IV), measured values of the magnetic moment at different values of the applied magnetic field over the temperature range 2-100 K obey a Brillouin function with spin 1/2.

High magnetic field Mössbauer studies of deoxymyoglobin, deoxyhemoglobin, and synthetic analogues.

Mössbauer spectra of deoxymyoglobin, deoxyhemoglobin, and the synthetic analogues, iron (II) 2-methylimidazole meso-tetraphenylporphyrin, and iron (II) 1,2-dimethylimidazole meso-tetraphenylporphyrin have been observed in high magnetic fields and over a wide range of temperature. At temperatures greater than 20 K all materials exhibit remarkably similar spectra, with anisotropic internal magnetic fields decreasing as 1/T. All have negative quadrupole interaction, and both this and the magnetic anisotropy imply that the orbital of the odd electron is prolate in the ground quintet, with little unquenched orbital angular momentum.

Mössbauer investigation of deoxymyoglobin in a high magnetic field. Orientation of the electric field gradient and magnetic tensors.

We have examined the Mössbauer spectra of deosymyoglobin in a 6 T magnetic field in the temperature range 4.2-195 K. Spectra were fitted by the least-squares method using a phenomenological model in which the internal magnetic hyperfine field was assumed to be related to the applied field by a temperature dependent tensor õmega.

Low temperature photodissociation studies of ferrous hemoglobin and myoglobin complexes by Mössbauer spectroscopy.

57Fe-enriched complexes of hemoglobin and myoglobin with CO and O2 were photodissociated at 4.2 degrees K, and the resulting spectra were compared with those of the deoxy forms. Differences in both quadrupole splitting and isomer shift were noted for each protein, the photoproducts having smaller isomer shift and larger quadrupole splitting than the deoxy forms.