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J Biomol Struct Dyn. 2018 Jul;36(9):2237-2248. doi: 10.1080/07391102.2017.1348988. Epub 2017 Jul 10.

Different amyloid aggregation of smooth muscles titin in vitro.

Author information

1
a Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences , Pushchino , Moscow Region 142290 , Russia.
2
b Pushchino State Institute of Natural Sciences , Pushchino , Moscow Region 142290 , Russia.
3
c Institute of Cell Biophysics, Russian Academy of Sciences , Pushchino , Moscow Region 142290 , Russia.
4
d Institute of Protein Research, Russian Academy of Sciences , Pushchino , Moscow Region 142290 , Russia.

Abstract

A comparative study of amyloid properties of the aggregates of smooth muscle titin (SMT) from chicken gizzard was carried out. These aggregates were formed in two solutions: 0.15 M glycine-KOH, pH 7.2-7.4 (SMT(Gly)) and 0.2 M KCl, 10 mM imidazole, pH 7.0 (SMT(KCl)). Electron microscopy data showed that SMT aggregates has an amorphous structure in both cases. The results of atomic-force microscopy demonstrated slight differences in morphology in two types of aggregates. The SMT(Gly) aggregates were represented as branching chains, composed of spherical aggregates approximately 300-500 nm in diameter and up to 35 nm in height. The SMT(KCl) aggregates formed sponge-like structures with strands of 8-10 nm in height. Structural analysis of SMT aggregates by X-ray diffraction revealed the presence of cross-β-sheet structure in the samples under study. In the presence of SMT(Gly) aggregates, thioflavine T fluorescence intensity was higher (~3-fold times) compared with that in the presence of SMT(KCl) aggregates. Congo red-stained SMT(Gly) aggregates had yellow to apple-green birefringence under polarized light, which was not observed for SMT(KCl) aggregates. Dynamic light scattering data showed the similar rate of aggregation for both types of aggregates, though SMT(KCl) aggregates were able to partially disaggregate under increased ionic strength of the solution. The ability of SMT to aggregation followed by disaggregation may be functionally significant in the cell.

KEYWORDS:

amyloid aggregation; amyloid structure; amyloids; protein aggregates; titin

PMID:
28661225
DOI:
10.1080/07391102.2017.1348988
[Indexed for MEDLINE]

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