Rosmarinic acid formation and differential expression of tyrosine aminotransferase isoforms in Anchusa officinalis cell suspension cultures |
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Authors: | Hajime Mizukami Brian E Ellis |
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Institution: | (1) Department of Plant Science, University of British Columbia, 2357 Main Mall, V6T 1Z4 Vancouver, B.C., Canada;(2) Present address: Faculty of Pharmaceutical Sciences, Nagasaki University, Bunkyo-machi 1-14, 852 Nagasaki, Japan |
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Abstract: | Time-course changes in rosmarinic acid (RA) formation and activities of tyrosine aminotransferase (TAT) isoforms were examined in Anchusa officinalis suspension cultures. Three TAT isoforms (TAT-1, TAT-3, TAT-4) were resolved by Mono-Q anion-exchange column chromatography. The proportion of the TAT-3 activity within the total TAT activity remained high regardless of the growth stage of the cultured cells. TAT-1 activity was positively correlated with the rate of RA biosynthesis during linear growth stage of the culture cycle, while TAT-4 activity was rapidly induced in conjunction with transfer to fresh medium coincident with a transient increase in RA synthesis. Based on these results, as well as the substrate specificity of each TAT isoform, it was concluded that both TAT-1 and TAT-4 are closely involved in RA biosynthesis. TAT-1 controls conversion of tyrosine to 4-hydroxyphenyl pyruvate, and TAT-4 acts by participating in the formation of tyrosine and phenylalanine via prephenate.Abbreviations PAL
phenylalanine ammonia-lyase
- TAT
tyrosine aminotransferase
- RA
rosmarinic acid |
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