Rotational correlation times of IgG and its fragments spin‐labeled at carbohydrate or protein moieties Spatially fixed position of the Fc carbohydrate

Slow conformational change in anti‐dansyl antibody as a consequence of hapten binding

“…PuriAbbreviations: Dns-or dansyl-, 1 dimethylamino-naphtalene5sulfonyl; Dnp, 2,4~i~~ophenyl flsevierl~orth-Noliand Riomedical Press fied anti-Dns antibodies (immunoglobulin G class) were spin-labelled by SL I (2,2,6,6-tetramethyl-Aloxylpiperidine~-amino-(~-dichlorotriazine~) in 0.05 M phosphate buffer (pH 7.3) for 3 days at 4"C, or by SL II (2,2,6,6-tetramethyl-~l-oxylpiperidine-4.iodoacetamide) in 0.1 M phosphate buffer (pH 8.0) for 7 days at 4*C. The unreacted SL I or SL II were removed by exhaustive dialysis and subsequent gel filtration on a Sephadex G-25 column [4]. The amount of bound spin-label was determined as in [4] and was found to be 2 mol label~mol antibody.…”

Spin‐label study of segmental flexibility of anti‐hapten antibodies

“…To remove the excess spin-label, exhaustive dialysis and gel filtration on Sephadex G-25 were used. The rotational correlation times Qwere determined as in [5,6]. The ESR spectra of spin-labeled proteins were run at 2O"C, and increasing sucrose concentrations (<40%) on a E-l 04 A Varian spectrometer.…”

“…Therefore, the 7 values were calculated from extrema (A,) which is apparently due to a more the shift of the high-field extrema AH(-1) after rigid immobilization of a fraction of the SL I moleincreasing the solution viscosity [5,6]. The calculacules ( fig.…”

“…The of the sample by buffer. Simultaneously, sharp peaks parameters /3 for Ai and A2 extrema were equal to appear that are characteristic of a free SL I label in 0.76 and 0.67, respectively [5,6]. Figure 2 shows the dependence of H'(-1) on (7'/~)fl for the precipitating and non-precipitating antibodies labeled by SL I. Parameters for calculation of the r values were obtained using these plots (table 1).…”

“…Recently, a variation of that method has been described that permits evaluation of rotation of a spin-label relative to a macromolecule [5]. Using this method, the rotational correlation times i of immunoglobulin molecules and their fragments were determined [6] and found to be in fair agreement with the results of fluorescence polarization experiments.…”