SEPARATION OF 2 INITIATOR TRANSFER RNAS FROM ESCHERICHIA-COLI
SEPARATION OF 2 INITIATOR TRANSFER RNAS FROM ESCHERICHIA-COLI
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DOI：
10.1016/0014-5793(68)80078-x
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发表时间：
1968-01-01
期刊：
影响因子：
3.5
通讯作者：
MARCKER K A
中科院分区：
文献类型：
--
作者：
CORY S;DUBE S K;MARCKER K A
最近，细菌起始子 tRNA tRNAfMet 的序列被阐明[11。在测序工作过程中，检测到次要的 tRNA B & et 在从氨基酸受体末端编号的位置 3 1 处具有 A 残基而不是 7Me 残基。两种 tRNAr 种类的相对比例估计为 7MeG 约为 75%，A 为 25%。进一步提供的证据表明，这种碱基变化可能是两种 tRNA 之间的唯一差异。该通讯描述了这两个 tRNAf 物种的部分分离，并证明这两个物种具有相同的编码特性。 s2P 标记的 tRNA 首先通过 DEAE Sephadex 色谱法分离，如其他地方所述 [2]。随后，纯化的 tRNAf 物质在苯甲酰化 DEAE 纤维素上进行色谱分析 [3]。图 1 显示了该实验的结果。含有 tRNAf 活性的第一个洗脱峰 (A) 是不对称的，表明两个同功受体 tRNAget 和 tRNAFt 部分分离。因此，tRNApf 是从洗脱曲线指定位置的级分中分离出来的。分离后，用 T1 或胰腺核糖核酸酶消化来自两个级分的样品。然后，使用 DEAE 纸张尺寸中的 7% 甲酸，通过常用的二维系统 [4] 对所得酶消化物进行分级。图2显示了各个tRNAf级分的T1核糖核酸酶“指纹”的比较。图 3 显示了胰腺核糖核酸酶“指纹”的类似比较。很明显，来自级分 1 的 tRNAet 含有相对少量的含“i”MeG 的序列（约 30%），同时具有高比例的相应的含 A 序列（约 70%）。来自分数 2 的 tRNA,, Met，在
Recently the sequence of the bacterial initiator tRNA, tRNAfMet, was elucidated [11. Durin the course of the sequence work a minor tRNA B & et was detected having an A residue instead of a 7Me residue at position 3 1 numbered from the amino acid acceptor end. The relative proportions of the two tRNAr species were estimated as approximately 75% with a 7MeG and 25% with an A. Evidence was further presented to show that this base change was probably the only difference between the two tRNAs. This communication describes the partial separation of these two tRNAf species and demonstrates that the two species have identical coding properties. tRNA, labelled with s2P was first separated by chromatography on DEAE Sephadex as desc&d elsewhere [2]. Subsequently the purified tRNAf species were subjected to chromatography on benzoylated DEAE cellulose [3]. Fig. 1 shows the result of such an experiment. The first eluted peak (A) containing the tRNAf activity is asymmetrical, suggesting a partial separation of two isoaccepting species, tRNAget and tRNAFt. For this reason tRNApf was isolated from fractions at the indicated positions of the elution profile. After their isolation samples from the two fractions were digested with Tl or pancreatic ribonuclease. The resulting enzymic digests were then fractionated by the usual two-dimensional system [4] using 7% formic acid in the DEAE paper dimension. Fig. 2 shows a comparison of the Tl ribonuclease “fingerprints” of the respective tRNAf fractions. Fig. 3 shows a similar comparison of the pancreatic ribonuclease “fingerprint”. It is evident that tRNAet from fraction 1 contains relatively small amounts of the ‘i’MeGcontaining sequence (about 30%), while having a high proportion of the corresponding A-containing sequence (about 70%). The tRNA,, Met from fraction 2, on the