ISSN:
1432-2048
Schlagwort(e):
Anthocyanin
;
L-α-Aminooxy-β-phenylpropionic acid
;
t-Cinnamic acid
;
Daucus
;
Phenylalanine ammonia lyase
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Abstract Cells of Daucus carota grown in a liquid medium produced large amounts of cyanidin as the only flavonoid aglycon. After inoculation in fresh medium a maximum activity of phenylalanine ammonia lyase (PAL; EC 4.3.1.5) was observed within 24 h. L-α-aminooxy-β-phenylpropionic acid (L-AOPP), thought to be a competitive inhibitor of PAL, inhibited cyanidin accumulation up to 80%. In order to study the regulatory role of PAL, the effects of L-AOPP and t-cinnamic acid, the product of the deamination of phenylalanine, were investigated. Cinnamic acid, applied in vivo (10-4 M), was not able to compensate for the inhibition of cyanidin production caused by L-AOPP (10-4 M) in the same sample. Carrot cells treated with L-AOPP exhibited a “super-induction” of PAL already described for gherkin hypocotyls (Amrhein and Gerhardt 1979). This effect was not influenced by t-cinnamic acid. L-AOPP seems to be a very specific inhibitor since it affected neither growth nor soluble protein content, whereas t-cinnamic acid inhibited both. Investigations on the content of soluble amino acids in L-AOPP-treated cells revealed a specific accumulation of soluble phenylalanine, whereas treatment with t-cinnamic acid led to an increase of amino acids in general, thus indicating that the latter compound has a rather unspecific effect on cellular metabolism. In vitro studies with PAL isolated from Daucus carota revealed that L-AOPP inhibited the enzyme at very low doses (K I=2.4·10-9), whereas t-cinnamic acid, by comparison, affected the enzyme at high concentrations (K I=1.8·10-4).
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00384567
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