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ID 11065
Eprint ID
11065
FullText URL
Title Alternative
Establishment of an Assay Method for βーCarotene-15,15'-Dioxygenase of Rat lntestine Mucosa and lts Enzymatic Properties
Author
Takagi, Shigeaki
Watanabe, Masanori
Nakajima, Akiko
Abstract
A central cleavage at 15, 15' position of βーcarotene has not been an established theory in absorption and metabolism, because an exenteric cleavage of βーcarotene for producing apocarotenals has been suggested. We considered that this problem was based only on the imperfection of the assay method for βーcarotene-15,15'-dioxygenase (BCDC) activity in vitro, and tried the establishment of this assay method by investigating cofactor activities together with other assy conditions. BCDO activity of rat intestina mucosa homogenate could not be detected with the known method by Goodman et al. SH reagents (GSH or DTT) and nicotinamide (NA) were essential for BCDO assay. NADH could take place with NA, but the product was retinol instead of retinal. NAD+ partially inhibited the enzyme activity. Optimum concentrations of other cofactors were decided under the following conditions : 1 mM GSH, 1 mM Fe2+, and 10 mM glycocholate. From these results, a good reproducibility of the in vitro assay for BCDO activity was obtained, and it was confirmed that the central cleavage theory presented by Goodman was reasonable.
Abstract Alternative
βーカロテンの15,15'位における中央開裂はβーカロテンの吸収・代謝において確立された説となっていない。それは分子端からの逐次開裂も示唆されているからである。このもんだいはin vitroにおけるβーcarotene-15, 15'dioxygenase (BCDO)活性測定法が不完全なために起こったのではないかと考え、補因子活性をそれ以外の測定条件と共に検討し、測定方法の確立を目指した。ラット小腸粘膜ホモジェネートのBCDO活性はGoodmanらの既知の方法によっては検出出来なかった。SH試薬(GSH,またはDTT)及びニコチンアミド(NA)はBCDO活性測定に必要であった。NAはNADHに置き換えられるが、生成物はレチナールの代わりにレチノールであった。NAD+はBCDOの活性を一部阻害する。他の補因子の最適濃度をこれらの条件下で決め、1 mM GSH, 1 mM Fe+, 10 mM glycocholateとした。これらの結果から、in vitro におけるBCDO活性測定が再現性良く行われることになり、Goodmanらによって提示されたβーカロテンの中央開裂が確認できた。
Keywords
βーcarotene cleavage enzyme
assay method
rat intestine mucosa
Published Date
1998-02
Publication Title
岡山大学農学部学術報告
Publication Title Alternative
Scientific reports of the Faculty of Agriculture, Okayama University
Volume
volume87
Issue
issue1
Publisher
岡山大学農学部
Publisher Alternative
Faculty of Agriculture,Okayama University
Start Page
29
End Page
34
ISSN
0474-0254
NCID
AN00033029
Content Type
Departmental Bulletin Paper
language
日本語
File Version
publisher
Refereed
False
Eprints Journal Name
srfa