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Saipin Sanghirun. Effects of some inhibitors on linamarin biosynthesis by cassava plantlets in tissue culture. Master's Degree(Biochemistry). Mahidol University. Mahidol University Library and Knowledge Center. : Mahidol University, 1993.
Effects of some inhibitors on linamarin biosynthesis by cassava plantlets in tissue culture
ผลของสารยับยั้งบางตัวต่อการสังเคราะห์ลินามารินในพืชสำปะ หลังที่เพาะเลี้ยงด้วยวิธีเพาะเลี้ยงเนื้อเยื่อ
Name: Saipin Sanghirun
LCSH:
Cassava
-- Anatomy & histology
Abstract:
Cyanogenic glucosides, mainly linamarin, in cassava cause cyanide toxicity related to cassava consumption. To eliminate this health hazard problem, a new variety free of the cyanogenic glucosides should be produced. In the present study, cassava plantlets in tissue culture were used to test whether the plantlets could grow normally when linamarin biosynthesis is inhibited. To do so, potential inhibitors of enzyme involved in the biosynthesis were first tested in vitro using soluble enzyme and tissue slices before final in vivo test in the cassava plantlets tissue culture. Five analogs of acetone cyanohydrin were found to completely inhibit the glucosyltransferase which catalyzed linamarin synthesis from acetone cyanohydrin. Pre-incubation experiment and kinetic analysis show that three analogs, isobutyraldehyde, 2-methyl-butyraldehyde and 2-methyl--2butanol, were competitive and reversible inhibitors. Although chlorobutanol exhibited reversible inhibition in the pre-incubation experiment, it caused an increase in both Km and V(,max) of acetone cyanohydrin. Isobutylamine was an irreversible inhibitor. The IC(,50) values of these five analogs were 0.0075, 0.02, 1.25, 12.0 and 26.5 mM, respectively. Incorporation of 14C-valine into linamarin using petiole slices from tissue cultured plantlets was completely inhibited by three analogs, chlorobutanol, 2-methylbutyraldehyde and isobutylamine, and partially inhibited by isobutyraldehyde and.2-methyl-2-butanol. The IC(,50) values were 0.9, 2.1, 2.9, 4.0 and 14 mM, respectively. Chlorpromazine and coumarin, two inhibitors of cytochrome P(,450) which were involved in the microsomal oxidation of valine into acetone cyanohydrin, also inhibited the radioactive incorporation. Their IC(,50) values were 0.5 and 1.0 mM, respectively. By using cassava plantlets in tissue culture, the linamarin synthesis was effectively inhibited while the growth was normal in the presence of 0.35-0.4 mM 2-methylbutyraldehyde, 0.5 mM chlorobutanol or 0.5 mM coumarin. On the contrary, 0.2 mM chlorpromazine caused retardation and abnormality of growth of the cassava plantlets without a significant decrease in the linamarin level while 0.5-1.0 mM isobutyraldehyde affected neither the growth nor the linamarin synthesis. The data suggested that cassava could grow normally when the linamarin synthesis was much suppressed.
Mahidol University. Mahidol University Library and Knowledge Center
Address:
NAKHONPATHOM
Email:
liwww@mahidol.ac.th
Name: Montri Chulavatnatol
Role:
Thesis Advisors
Name: Tipaporn Limpaseni
Role:
Thesis Advisors
Name: Pichit Tosukhowong
Role:
Thesis Advisors
Created:
1993
Modified:
2018-02-22
Issued:
2018-02-22
วิทยานิพนธ์/Thesis
application/pdf
eng
DegreeName: Master of Science
Level: Master's Degree
Descipline: Biochemistry
Grantor: Mahidol University
ใช้เวลา
0.296107 วินาที
Saipin Sanghirun
| Title | Contributor | Type |
|---|---|---|
| Effects of some inhibitors on linamarin biosynthesis by cassava plantlets in tissue culture
มหาวิทยาลัยมหิดล Saipin Sanghirun | Montri Chulavatnatol Tipaporn Limpaseni Pichit Tosukhowong | วิทยานิพนธ์/Thesis |
Montri Chulavatnatol
Tipaporn Limpaseni
Pichit Tosukhowong