Antonny B, Bigay J, Chabre M
CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France.
FEBS Lett. 1990 Jul 30;268(1):277-80. doi: 10.1016/0014-5793(90)81027-l.
Activation of transducin-GDP by NaF is mainly mediated by aluminofluorde or beryllofluoride complexes acting as GTP gamma-phosphate analogs. In millimolar magnesium, NaF at concentrations above 3 mM is active even in the absence of aluminium or beryllium. This activation has a Hill coefficient of 3 with respect to F-, and its rate is linear with respect to Mg2+ concentrations above 2 mM. Upon fluoride dilution, inactivation rate is hundreds of times faster than for aluminofluoride-activated T alpha GDP. We propose that at high NaF concentrations, 3 hydrogen-bonded fluorides in the gamma-phosphate site of T alpha GDP entrap a magnesium counterion and this induces the transconformation to the T alpha GTP form.
氟化钠对转导素 - GDP的激活主要由铝氟化物或铍氟化物配合物介导，它们作为GTPγ - 磷酸类似物起作用。在毫摩尔浓度的镁存在下，浓度高于3 mM的氟化钠即使在没有铝或铍的情况下也具有活性。这种激活相对于F - 的希尔系数为3，并且其速率相对于高于2 mM的Mg2 + 浓度呈线性关系。在氟化物稀释时，失活速率比铝氟化物激活的TαGDP快数百倍。我们提出，在高氟化钠浓度下，TαGDPγ - 磷酸位点中的3个氢键结合的氟化物捕获一个镁抗衡离子，这诱导了向TαGTP形式的转构象。
