A sulfhydryl group specific spin label has been used to study membrane proteins in erythrocyte ghosts from patients with myotonic muscular dystrophy (MyD). The resulting electron spin resonance spectra of labeled permeable MyD and control ghosts demonstrate two chief populations of sulfhydryl groups, one weakly immobilized, the other strongly immobilized. Approximately one-third of the labeled sulfhydryl groups are in weakly immobilized sites which, based on their nitrogen hyperfine splitting value and their accessibility to both spin label and ascorbate, appear to be located near the membrane surface in a highly polar environment. Strongly immobilized sulfhydryl groups appear to be located both at the membrane surface and deep within the lipid bilayer. While the linewidths of each class of sites are equal in control and MyD membranes, the ratio of the spectral amplitude of the spin label attached to weakly immobilized sites to that of strongly immobilized sites is significantly greater in MyD membranes (P ≅ 0.001). This effect is due to a decreased incorporation of the spin label into the strongly immobilized sulfhydryl group sites and suggests that membrane organizational or protein conformational differences exist between MyD and control erythrocyte membranes.
|Number of pages||9|
|Journal||Archives of Biochemistry and Biophysics|
|State||Published - Nov 1976|
Bibliographical noteFunding Information:
1 This work was supported in part by National Institutes of Health NINDS Grant 1 F22 NSO-1364-01 to D.A.B., NSF Grant GP-22546, NIH Grant NSO 7872, Multiple Sclerosis Society Grant 558-D-S, NIH Grant NS 12213, a Basil O’Connor Starter Research Grant from the National Foundation March of Dimes, and the Multiple Sclerosis Society Grant 923-A-2. 4 NIH Postdoctoral Fellow, 1974-1975. Present address: Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506. ’ Abbreviations used: esr, electron spin resonance; SH, sulfhydryl; MyD, myotonic muscular dystrophy; RBC, red blood cell; MAL-6, 2,2,6,6-tetramethylpiperidine-1-oxyl-4-maleimide; PCMB, parachloromercuribenzoate; NEM, N-ethyl maleimide; PBS, phosphate-buffered saline, containing 5 mM sodium phosphate, 150 mM NaCl, pH 8.0; 5P8, 5 mM sodium phosphate buffer, pH 8.0; SDS, sodium dodecyl sulfate. TCA, trichloroacetic acid; EGTA, ethylene glycobis(aminoethyl)-NJ’-tetraacetic acid; S, strongly immobilized; W, weakly lized; and DTNB, 5,5-dithiobis(2-nitrobenzoic
ASJC Scopus subject areas
- Molecular Biology