Key Role of Fe2+ in Epithiospecifier Protein Activity

WilliamsDavidJ, CritchleyChrista, PunSharon, ChalihaMridusmita, O'Hare, Timothy and JamesNSeiber (2010) Key Role of Fe2+ in Epithiospecifier Protein Activity. Journal of Agricultural and Food Chemistry, 58 15: 8512-8521. doi:10.1021/jf904532n

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Author WilliamsDavidJ
O'Hare, Timothy
Title Key Role of Fe2+ in Epithiospecifier Protein Activity
Formatted title
Key Role of Fe2+ in Epithiospecifier Protein Activity
Journal name Journal of Agricultural and Food Chemistry   Check publisher's open access policy
ISSN 0021-8561
Publication date 2010-07-01
Sub-type Article (original research)
DOI 10.1021/jf904532n
Volume 58
Issue 15
Start page 8512
End page 8521
Total pages 10
Place of publication United States
Publisher American Chemical Society
Language eng
Subject C1
820215 Vegetables
060101 Analytical Biochemistry
Formatted abstract
The chemical nature of the hydrolysis products from the glucosinolate−myrosinase system depends on the presence or absence of supplementary proteins such as epithiospecifier proteins (ESPs). ESPs promote the formation of epithionitriles from terminal alkenyl glucosinolates and, as recent evidence suggests, simple nitriles at the expense of isothiocyanates. From a human health perspective isothiocyanates are the most important because they are major inducers of carcinogen-detoxifying enzymes. Fe2+ is an essential factor in ESP activity, although several recent studies have highlighted discrepancies in the understanding of the ESP−iron interaction. To investigate further the role iron species play in regulating ESP activity, four ESP-containing seedpowders were analyzed for ESP and myrosinase activities, endogenous iron content, and glucosinolate degradation products after the addition of iron species, specific chelators, and reducing agents. For the first time this paper shows the effect of these additions on the hydrolysis of individual glucosinolates that constitute the total pool. Aged seeds and 3-day seedlings were also tested to investigate the effects of seed storage and early plant development on iron levels and ESP activity. The four ESP-containing plant systems tested gave two distinctive responses, thus providing strong evidence that ESPs vary markedly in their Fe2+ requirement for activity. The results also indicated that reduction of ferric to ferrous iron drives variations in ESP activity during early plant development. The reverse oxidation reaction provided a convincing explanation for the loss of ESP activity during seed storage. Aged seeds produced seedlings with substantially lower ESP activity, and there was a concomitant loss in germination rate. It was concluded that manipulation of endogenous iron levels of ESP-containing plants could increase the conversion of glucosinolates to isothiocyanates and enhance potential health benefits.
Keyword Epithiospecifier protein activity
total and ferrous iron
nitrile formation
Benzylglucosinolate degradation
Thioglucoside Glucohydrolase
Antiproliferative activity
Glucosinolate hydrolysis
Sulforaphane Nitrile
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2011 Collection
School of Biological Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 13 times in Thomson Reuters Web of Science Article | Citations
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Created: Wed, 04 Aug 2010, 20:27:22 EST by Joni Taylor on behalf of School of Biological Sciences