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Biomedical subjects

J G Stollery

Publications and source records attributed to J G Stollery.

8 recordsLinked to original sources
PubMed1982

Binding of myelin basic protein to phospholipid micelles.

Resonances of 1H NMR spectra (360 MHz) due to several individual substituents of myelin basic protein reconstituted into phospholipid micelles have been resolved and assigned. With the aid of spin echo techniques to remove overlapping signals in the region of 2-3 ppm, singlet resonances due to the two myelin basic protein methionine S--CH3 groups (Met-20 and Met-167) and the Ala-1 N-acetyl methyl group were observed. In the presence of sufficient lysophosphatidylcholine to fully bind the protein, differential broadening occurred for Met S--CH3 resonances; Met-20 lost about 40% of its original integrated intensity (while displaying no significant line broadening) but Met-167 and N-acetyl-Ala-1 resonances did not appear to be influenced by lipid. The differential broadening of the Met-20 (versus the Met-167 and N-acetyl-Ala-1) resonances was proposed to arise from (a) specific restriction to local molecular motion of the Met-20 (but not Met-167) side chain (i.e. due to its penetration into the hydrophobic micelle lipid matrix or its proximity to specific protein/lipid electrostatic sites); or (b) transmitted dynamic effects of overall protein binding to micellar particles (due to the relatively fewer degrees of rotational freedom available to Met-20 versus N-acetyl-Ala-1 and Met-167 near protein termini). Evidence favoring the latter alternative is presented.

Animals↗
PubMed1980

Nature of the cysteinyl residues in lipophilin from human myelin.

Ellman's reagent was used to investigate the status and exposure of the cysteinyl residues in lipophilin, a proteolipid apoprotein from human myelin. The hydrolyzed protein contained 3.5 to 4.5 cysteines per molecule, which increased to 11 after complete reduction. The native protein was thought to contain three disulfide bonds and five free sulfhydryl groups, which undergo partial oxidation during purification. Exposure of -SH groups in the aqueous protein was minimal, even in the presence of 6 M guanidinium chloride, suggesting a location in hydrophobic domains not disrupted by this reagent. In the helicogenic solvent 2-chloroethanol, the full complement of -SH groups could not be revealed, even with the addition of sodium dodecyl sulfate; a difference of two sulfhydryls between intact and hydrolyzed protein was consistently observed. Similar sulfhydryl reactivity toward iodoacetamide was also established in this solvent. Sulfhydryl assays on whole myelin in 2-chloroethanol indicated that the occurrence of -SH groups in the proteolipid component was at least as high as in the purified apoprotein. Lipophilin was reduced and alkylated with 4-vinylpyridine at 10 of its cysteinyl residues. The modified protein adopted a beta structure under conditions where lipophilin is normally highly alpha-helical, and was also less helical than usual in 2-chloroethanol; however, it was still abnormally resistant to denaturation by guanidinium chloride. Modified lipophilin contained as many ester groups as the intact protein; thus, it appeared unlikely that the long chain fatty acids associated with the protein were attached to cysteine residues.

Acetylcholine↗
PubMed1979

Phase changes of cardiolipin vesicles mediated by divalent cations.

Small unilamellar vesicles were prepared from cardiolipin and produced the hexagonal II phase when dialyzed against CaCl2 or MgCl2. Upon removal of the cation by dialysis against EDTA large unilamellar vesicles were formed. The events of the transition from the lamellar to hexagonal phase and back to the lamellar phase are described.

Calcium↗