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Improvement of leaf aldehyde production.

Siangdung, Wipanwan.

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Improvement of leaf aldehyde production.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Improvement of leaf aldehyde production./
Author:	Siangdung, Wipanwan.
Description:	163 p.
Notes:	Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0129.
Contained By:	Dissertation Abstracts International67-01B.
Subject:	Agriculture, Agronomy. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3200337
ISBN:	9780542472831

Improvement of leaf aldehyde production.
Siangdung, Wipanwan.

Improvement of leaf aldehyde production. - 163 p.

Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0129.

Thesis (Ph.D.)--University of Kentucky, 2006.

Leaf aldehyde, 2(E)-hexenal, is an important flavor and aroma ingredient in foods and beverages. It can also be used to treat plants and plant products such as fruit for enhanced disease resistance, shelf life, and quality, and reduce food-borne disease organisms on food handling equipment. Leaf aldehyde is currently valued as much as

ISBN: 9780542472831Subjects--Topical Terms:

1018679
Agriculture, Agronomy.

Improvement of leaf aldehyde production.
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020 $a 9780542472831
035 $a (UMI)AAI3200337
035 $a AAI3200337
040 $a UMI $c UMI
100 1 $a Siangdung, Wipanwan. $3 1917723
245 1 0 $a Improvement of leaf aldehyde production.
300 $a 163 p.
500 $a Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0129.
500 $a Director: David Hildebrand.
502 $a Thesis (Ph.D.)--University of Kentucky, 2006.
520 $a Leaf aldehyde, 2(E)-hexenal, is an important flavor and aroma ingredient in foods and beverages. It can also be used to treat plants and plant products such as fruit for enhanced disease resistance, shelf life, and quality, and reduce food-borne disease organisms on food handling equipment. Leaf aldehyde is currently valued as much as $1 00 per kg and the demand for natural leaf aldehyde in food industries has significantly increased over 70% in the past 10 years. The C6 aldehydes and corresponding alcohols are derived from linoleic and alpha-linolenic acids. Four enzymes are involved in the biosynthetic pathway leading to their formations: lipoxygenase, hydroperoxide lyase (HL), (3Z,2E)-enal isomerase, and alcohol dehydrogenase (ADH). Currently, watermelon leaves are a high producing natural source of leaf aldehyde apparently due to very high activity of HL.
520 $a In this work, the HLs from Arabidopsis, tobacco ( Nicotiana tabacum) and watermelon (Citrullus lanatus) were investigated. Here, the tobacco HL was cloned for the first time (GenBank accession no. DQ129870) and its cDNA encoded 497 amino acids (&sim;55.7 kDa), and shared homology with a P450 (CYP74B). The heme binding cysteine was recognizable at position 459. The NtHL showed 59 and 62 % identity to Arabidopsis HL (AtHL) and watermelon HL (ClHL) respectively. Since watermelon HL was reported as one of the highest leaf aldehyde producers, the activity characterization of HL was investigated. The genes encoding ClHL, AtHL and NtHL were expressed in Escherichia coli and the corresponding enzymes were characterized. It was found that higher activities of HLs were achieved when the E. coli media was supplemented with a heme precursor (delta-levulinic acid). In this work, removal of putative N-terminal extension sequences of AtHL, NtHL and ClHL did not show increases of HL activities, this indicated that none contained N-terminal targeting sequences. High HL activity was mainly found in the E. coli membrane fractions which supported the notion that HL was a membrane-associated protein. Biochemical studies showed the Km of AtHL, NtHL and ClHL were 540.3 +/- 312, 236.4 +/- 93.9 and 281.6 +/-64.4 muM. The Vmax of AtHL, NtHL and ClHL were 39.3 +/- 15.1, 42.9 +/- 8.3 and 396.8 +/- 48.9 pmol/min/mg protein, respectively. The Vmax/K m of ClHL was 1.41, which was 19.6 and 7.8- fold higher than those of AtHL and NtHL, respectively. Vmax/K m values of those three HLs indicated that the ClHL had the highest efficiency of catalysis. Also, with the same period of a storage time, the ClHL could retain higher activity than the others, suggesting the ClHL was more stable. (Abstract shortened by UMI.)
590 $a School code: 0102.
650 4 $a Agriculture, Agronomy. $3 1018679
650 4 $a Agriculture, Food Science and Technology. $3 1017813
650 4 $a Biology, Plant Physiology. $3 1017865
690 $a 0285
690 $a 0359
690 $a 0817
710 2 0 $a University of Kentucky. $3 1017485
773 0 $t Dissertation Abstracts International $g 67-01B.
790 1 0 $a Hildebrand, David, $e advisor
790 $a 0102
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3200337