Abstract
The increment of Lys-sensitive aspartokinase (EC 2.7.2.4) activity during in vitro culture of carrot (Daucus carota, cv. Oogata sanzum) root tissue was explained in terms of derepression caused by an earlier decrease in the endogenous level of Lys, a possible end product repressor. Tissue content of free Lys decreased to about 1/3 of the initial level after 1 day of culture and no Lys was detected in the 2nd day. Inclusion of Lys (0.1-1.0 mM) in the culture medium resulted in a specific suppression of increase in Lys-sensitive aspartokinase activity without affecting the increase in Thr-sensitive aspartokinase activity.