EurekaMag.com logo
+ Site Statistics
References:
53,214,146
Abstracts:
29,074,682
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Reinvestigation of the sulfhydryl reactivity in bovine brain s100b beta beta protein and the microtubule associated tau proteins calcium stimulates disulfide cross linking between the s100b beta subunit and the microtubule associated tau 2 protein






Biochemistry 27(8): 2728-2736

Reinvestigation of the sulfhydryl reactivity in bovine brain s100b beta beta protein and the microtubule associated tau proteins calcium stimulates disulfide cross linking between the s100b beta subunit and the microtubule associated tau 2 protein

Zn2+ and Ca2+ affect the conformation of bovine brain S100b (.beta.beta.) protein and the exposure of its Cys-84.beta., Zn2+ binding to high-affinity sites of native S100b protected the sulfhydryl groups against the thiol-specific reagent 5,5'-dithiobis(2-nitrobenzoate) and antagonized the Ca2+-stimulated reactivity of Cys-84.beta. toward the reagent. Spectroscopic studies on the fluorescence properties of labeled S100b with the fluorescent probes bimane and acrylodan at Cys-84.beta. confirmed the antagonist effect of Ca2+ and Zn2+ with respect to the conformational properties of the protein. Measurements of fluorescence dynamics on bimane-labeled S100b indicated that the slow monomer-dimer equilibrium that characterizes the apoprotein at micromolar concentrations was shifted to the monomer form in the presence of Zn2+, a fact that could explain the previously reported Zn2+-dependent increase of S100b protein affinity for calcium. The difference in the effects of Ca2+ and Zn2+ on the reactivity of Cys-84.beta. in S100b was confirmed when we observed that Ca2+ and Zn2+ have opposite actions on the formation of disulfide bridges between Cys-84.beta. of the S100b .beta.-subunit and sulfhydryl groups on the microtubule-associated .tau.(2) protein. Ca2+ stimulated the covalent complex formation whereas Zn2+ inhibited it. We suggest that Zn2+ may have a modulatory function on Cys-84.beta. reactivity in the S100b .beta.-subunit in vivo. Two types of divalent complexes between .tau.(2) and .beta.-subunit were formed in the presence of Ca2+, an equimolar complex .sigma.(2)-.beta.1 and a complex of one molecule of .tau.(2) with two .beta.-subunits, .tau.(2)-.beta.2. At pH 8.3, the dissociation constant for the equimolar complex was estimated to be approximately 0.3 .mu.M, and the rate constant for the cross-linking reaction was estimated to be 0.2 .mu.M.cntdot.min-1. The rapid attack of .tau.(2) in rupturing disulfide bridges in oxidized S100b demonstrated the strong nucleophilicity of the sulfhydryl group(s) in .sigma.(2). Analogous attacks on other proteins, however, did not lead to disulfide complex formation, indicating that the specific, noncovalent complexation between .tau. protein and S100b preceded disulfide formation and interchange. The result is a rather specific production of disulfide oligomers. The insoluble oligomers of the neurofibrillary tangle that characterizes Alzheimer's brain might be an example of such a situation.

(PDF 0-2 workdays service: $29.90)

Accession: 006292981



Related references

Reinvestigation of the sulfhydryl reactivity in bovine brain S100b (.beta..beta.) protein and the microtubule-associated .tau. proteins. Calcium stimulates disulfide cross-linking between S100b .beta.-subunit and the microtubule-associated .tau.(2) protein. Biochemistry 27(8): 2728-2736, 1988

Reinvestigation of the sulfhydryl reactivity in bovine brain S100b (beta beta) protein and the microtubule-associated tau proteins. Ca2+ stimulates disulfide cross-linking between the S100b beta-subunit and the microtubule-associated tau(2) protein. Biochemistry 27(8): 2728-2736, 1988

Reinvestigation of the sulfhydryl reactivity in bovine brain S100b (bb) protein and the microtubule-associated t proteins. Ca2+ stimulates disulfide cross-linking between the S100b b-subunit and the microtubule-associated t(2) protein. Biochemistry (American Chemical Society) 27: 28-36, 1988

Ions binding to S100 proteins. I. Calcium- and zinc-binding properties of bovine brain S100 alpha alpha, S100a (alpha beta), and S100b (beta beta) protein: Zn2+ regulates Ca2+ binding on S100b protein. Journal of Biological Chemistry 261(18): 8192-8203, 1986

S100b protein calcium binding properties and calcium dependent interactions with the microtubule associated tau proteins s100b regulates tau phosphorylation by protein kinase. Norman, A W , T C Vanaman And A R Means (Ed ) Calcium-Binding Proteins in Health And Disease; Fifth International Symposium, Pacific Grove, California, Usa, November 30-December 5, 1986 Xix+629p Academic Press, Inc : San Diego, California, Usa; London, England, Uk Illus 555-557, 1987

The calcium binding sequence in bovine brain s100b protein beta subunit a spectroscopic study. Biochemical Journal 264(1): 79-86, 1989

The Ca2+-binding sequence in bovine brain S100b protein beta-subunit. A spectroscopic study. Biochemical Journal 264(1): 79-85, 1989

Ions binding to S100 proteins. Calcium- and zinc-binding properties of bovine brain S100aa, S100a (ab), and S100b (bb) protein: Zn2+ regulates Ca2+ binding on S100b protein. The Journal of Biological Chemistry 261: 92-203, 1986

Bimane- and acrylodan-labeled S100 proteins. Role of cysteines-85.alpha. and -84.beta. in the conformation and calcium binding properties of S100aa and S100b (.beta..beta.) proteins. Biochemistry 25(22): 6934-6941, 1986

Interactions between the microtubule associated tau proteins and s100b regulate tau phosphorylation by the calcium calmodulin dependent protein kinase ii. Journal of Biological Chemistry 263(12): 5876-5883, 1988