Vulimiri S V, Nayak R
Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore.
Biochem Mol Biol Int. 1994 May;33(1):147-54.
5-fluorouracil (FUra) has been shown to modulate the aminoacylation function of rat liver tRNA. The present study was aimed at studying the structure-function relationship of FUra-substituted tRNA. Male Wistar rats (2-3 month old) were given a single i.p. injection of FUra at 50, 250, or 500 mg/kg body wt. and FUra-substituted total liver tRNA, i.e. tRNA(FUra50, 250, and 500, respectively, were isolated 3 h later. Normal tRNA (tRNA(N)) was isolated from saline-treated control rats. Thermal denaturation studies showed higher melting temperatures for tRNA(FUra) compared to tRNA(N). Heat denaturation followed by renaturation of total tRNA did not affect the activity of tRNA(N) and tRNA(FUra50), where as tRNA(FUra250 and 500) lost 35% and 72% of activity, respectively, compared to the corresponding group of non-denatured tRNA. Antibodies specific to rat liver tRNA recognized normal and FUra-substituted tRNA in the order of tRNA(N) > tRNA(FUra50) > or = tRNA(FUra250) > tRNA(FUra500) in an avidin-biotin micro-enzyme linked immunosorbant assay. tRNA(N) or tRNA(FUra50) preincubated with tRNA antiserum showed 74% and 59% of aminoacylation activity, respectively, compared to that of corresponding tRNA preincubated with normal rabbit IgG. However, activities of similarly treated tRNA(FUra250 and 500) were not affected. The observations of possible changes in the secondary structure of rat liver tRNA upon incorporation of FUra are discussed.
5-氟尿嘧啶（FUra）已被证明可调节大鼠肝脏tRNA的氨酰化功能。本研究旨在研究FUra取代的tRNA的结构-功能关系。给2-3月龄的雄性Wistar大鼠腹腔注射一次50、250或500mg/kg体重的FUra，3小时后分离出FUra取代的肝脏总tRNA，即分别为tRNA(FUra50、250和500)。从生理盐水处理的对照大鼠中分离出正常tRNA（tRNA(N)）。热变性研究表明，与tRNA(N)相比，tRNA(FUra)具有更高的解链温度。总tRNA热变性后复性并不影响tRNA(N)和tRNA(FUra50)的活性，而与相应的未变性tRNA组相比，tRNA(FUra250和500)分别丧失了35%和72%的活性。在抗生物素蛋白-生物素微酶联免疫吸附测定中，大鼠肝脏tRNA特异性抗体识别正常和FUra取代tRNA的顺序为tRNA(N) > tRNA(FUra50) > 或 = tRNA(FUra250) > tRNA(FUra500)。与用正常兔IgG预孵育的相应tRNA相比，用tRNA抗血清预孵育的tRNA(N)或tRNA(FUra50)分别显示出74%和59%的氨酰化活性。然而，同样处理的tRNA(FUra250和500)的活性不受影响。本文讨论了FUra掺入后大鼠肝脏tRNA二级结构可能发生变化的观察结果。
