Interaction of β-lactoglobulin with chaperonin GroEL

Sakai, Kazuko; Hoshino, Masaru; Goto, Yuji

Proceedings of the Indian National Science Academy, 2002, 68(4A), 341-347

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Identifier to cite or link to this item: https://hdl.handle.net/11094/71264

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Title
Interaction of β-lactoglobulin with chaperonin GroEL
Creator
CreatorName
Sakai, Kazuko
NRID
1000070304053 1000070304053
CreatorName
Hoshino, Masaru
NRID
1000040153770 1000040153770
researchmap permalink
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CreatorName
Goto, Yuji
Subject
β-Lactoglobulin
GroEL
Protein Folding
Substrate Recognition
Salt Effects
Hydrophobic Interaction
Description
Sakai, Kazuko, Hoshino, Masaru and Goto, Yuji "Interaction of β-lactoglobulin with chaperonin GroEL", Proceedings of the Indian National Science Academy, 68, 4A, 341-347, Indian National Science Academy, 2002
Abstract
The roles of electrostatic and hydrophobic interactions in the substrate recognition of GroEL were studied with bovine β-lactoglobulin as a substrate. We previously reported that, although the native state of β-lactoglobulin does not interact with GroEL, the modified protein in which the two disulfide bonds were reduced formed a stable complex. To clarify the extent of denaturation necessary for the interaction, we examined the interaction of GroEL with the intermediate state of β-lactoglobulin in which the free thiol group was specifically modified with 5,5' -dithiobis (2-nitrobenzoic acid). The thiol-modified β-lactoglobulin formed a complex with GroEL as measured by size-exclusion chromatography, indicating that moderate denaturation is enough for the interaction. We then measured the interaction between GroEL and the refolding intermediate of the disulfide intact β-lactoglobulin. Although the interaction was marginal under low salt conditions, notable interaction was observed by the addition of KCI. Since pl values of GroEL and β-lactoglobulin are 4.7 and 4.5, respectively, the addition of salt was considered to shield the unfavourable charge repulsion. Tryptophyl fluorescence of the kinetic intermediate indicated that tryptophan residues were buried upon binding. These results confirmed the previous view that suppression of the unfavourable electrostatic repulsion in addition to exertion of favourable hydrophobic interaction is important for the binding of substrate proteins to GroEL.
Publisher
Indian National Science Academy
Source Title
Proceedings of the Indian National Science Academy
Volume (Issue)
68(4A)
Page
341-347
Date of Issued
2002-07
Language
English
Handle URL
https://hdl.handle.net/11094/71264
PISSN
03700046
NCID
AA12158303
Access Rights
open access
CopyRight
This article is licensed under a Creative Commons Attribution 4.0 International License.
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Category
学術雑誌論文 Journal Article