Reduction of aggregation of β-lactoglobulin during heating by dihydrolipoic acid

Wijayanti, Heni B., Oh, H. Eustina, Sharma, Ranjan and Deeth, Hilton C. (2013) Reduction of aggregation of β-lactoglobulin during heating by dihydrolipoic acid. Journal of Dairy Research, 80 4: 383-389. doi:10.1017/S0022029913000332


Author Wijayanti, Heni B.
Oh, H. Eustina
Sharma, Ranjan
Deeth, Hilton C.
Title Reduction of aggregation of β-lactoglobulin during heating by dihydrolipoic acid
Journal name Journal of Dairy Research   Check publisher's open access policy
ISSN 0022-0299
1469-7629
Publication date 2013-01-01
Year available 2013
Sub-type Article (original research)
DOI 10.1017/S0022029913000332
Open Access Status DOI
Volume 80
Issue 4
Start page 383
End page 389
Total pages 7
Place of publication Cambridge, United Kingdom
Publisher Cambridge University Press
Language eng
Abstract Prevention of the heat-induced aggregation of β-lactoglobulin (β-Lg) would improve the heat stability of whey proteins. The effects of lipoic acid (LA, or thioctic acid), in both its oxidised and reduced form (dihydrolipoic acid, DHLA), on heat-induced unfolding and aggregation of β-Lg were investigated. LA/DHLA was added to native β-Lg and the mixture was heated at 70, 75, 80 or 85 °C for up to 30 min at pH 6·8. The samples were analysed by Polyacrylamide Gel Electrophoresis (PAGE) and Size-exclusion HPLC (SE-HPLC). LA was not as effective as DHLA in reducing the formation of aggregates of heated β-Lg. Heating β-Lg with DHLA resulted in formation of more β-Lg monomers (due to dissociation of native dimers) and significantly less β-Lg aggregates, compared with heating β-Lg alone. The aggregates formed in the presence of DHLA were both covalently linked, via disulphide bonds, and non-covalently (hydrophobically) linked, but the amount of covalently linked aggregates was much less than when β-Lg was heated alone. The results suggest that DHLA was able to partially trap the reactive β-Lg monomer containing a free sulphydryl (-SH) group, by forming a 'modified monomer', and to prevent some sulphydryl-sulphydryl and sulphydryl-disulphide interactions that lead to the formation of covalently linked protein aggregates. The effects of DHLA were similar to those of N-ethylmaleimide (NEM) and dithio(bis)-p-nitrobenzoate (DTNB). However, the advantage of using DHLA over NEM and DTNB to lessen aggregation of β-Lg is that it is a food-grade compound which occurs naturally in milk.
Keyword Agregates
Aggregation
Dihydrolipoic Acid
Dimers
Heating
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Agriculture and Food Sciences
Official 2014 Collection
 
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