TY  - JOUR
PY  - 2005//
TI  - Mechanism-based irreversible inhibitors of cytokinin dehydrogenase
JO  - Journal of plant physiology
A1  - Suttle, Jeffrey C.
A1  - Mornet, Rene
SP  - 1189
EP  - 1196
VL  - 162
IS  - 11
N2  - The effects of three N(6)-substituted aminopurine derivatives containing either allenic or acetylenic side-chains on in vitro and in vivo cytokinin dehydrogenase (CKX; EC 1.5.99.12) activities were determined. At concentrations < or = 100 microM, the acetylenic derivative (HA-2) had no effect on in vitro CKX activity. In contrast, the two allenic derivatives (HA-1, HA-8) inhibited in vitro CKX activity in a dose-dependent manner with 50% inhibition occurring at HA-1 and HA-8 concentrations of 9.0 and 0.4 microM (respectively). HA-8 inhibited the degradation of both the free bases and ribosides of N6-(2-isopentenyl)adenine and zeatin. Pretreatment with HA-8 inhibited CKX activity in both a time- and concentration-dependent manner. In contrast to the reversible phenylurea inhibitor N-(chloro-4-pyridyl)-N'-phenylurea, inhibition of CKX activity by HA-8 was not relieved by 24 h of dialysis. Both HA-1 and HA-8 (but not HA-2) inhibited the metabolism of exogenous [3H]-N(6)-(2-isopentenyl)adenosine in excised aseptic potato (Solanum tuberosum) leaves. These results demonstrate that HA-8 is a mechanism-based irreversible (suicide) inhibitor of CKX and indicate that it may be useful in determining the role of CKX in cytokinin homeostasis in planta.<p /> <p>Language: en</p>
LA  - en
SN  - 0176-1617
UR  - http://dx.doi.org/10.1016/j.jplph.2005.03.012
ID  - ref1
ER  -