Spin—spin interaction between iminoxyl radicals localised in antibody combining sites

Spin-labeled carbohydrates

“…124 This result is in agreement with the concept that the A conformer represents an inflexible state of the immunoglobulins. 107 The proposal was made that the lower segmental flexibility of IgE is caused by an additional bonding between Fab segments which results in their joint rotation around the Fc segment.124 This peculiarity of the IgE structure agrees with the fact that the IgE antibodies do not form a precipitate after combining with the antigen. 124 The carbohydrate group of IgE(Yu) was spin labeled.105…”

“…125 These results are in contrast to those obtained in experiments in which the spin label was bound to the protein component of the IgG antibody.107"109 For example, antibodies spin labeled on protein with either 35 or 7b were prepared against immunoglobulins or other substances. 107 The ESR spectra of the resulting complexes between labeled antibodies and antigens indicated an increase in the less mobile A conformer. 107 The rc values of the spin label increased, corresponding to a decreased rotational mobility of the label attached to the protein of the Fab segment.…”

“…107 The ESR spectra of the resulting complexes between labeled antibodies and antigens indicated an increase in the less mobile A conformer. 107 The rc values of the spin label increased, corresponding to a decreased rotational mobility of the label attached to the protein of the Fab segment. This apparent conformational change was the same for all antibodies and was not dependent on the particular antigen or its site of attachment to the immunoglobulin molecule.107 '108 This increase in rc values occurred for several combinations, including donkey antibodies + human IgG, rabbit antibodies + bovine IgG, and rabbit anti-bodies + hemoglobin (Hb).…”

“…The halftime for full equilibration of this amino sugar across membranes of halobacterial vesicles was 15 h as compared to half-times of less than 100 ms for more lipophilic nitroxyls such as 2-6.38 Urea Formation. Labeled sugars containing a thiourea group, 78 nitroxyl isothiocyanate 8 (Scheme XIX).25 Compound 77 was prepared by reduction of (p-nitrophenyl)-/3-Dglucoside (128). This method appears to be a convenient route to some unblocked monosaccharide derivatives.…”

“…109 sites on the IgG molecule but rather to an equilibrium between the A and B states of the spin label. 107 The values of the distance between the outer wide lines (or maximum hyperflne splitting) were plotted vs. the temperature to viscosity (T:ri) ratio. 106 The measurements were made at constant temperature (0 °C), and the solution viscosity was increased by the addition of sucrose.…”