Brudzyńska K, Zbikowski W, Walter Z
Acta Biochim Pol. 1982;29(1-2):65-79.
DNA-dependent RNA polymerases from calf thymus tissue were solubilized and purified. Among seven chromatographically different forms of RNa polymerases obtained on DEAE-cellulose or DEAE-Sephadex chromatographies three subclasses of enzymes C were found. General enzymatic properties as: a moderate sensitivity to alpha-amanitin, divalent cation requirements, the preference for native DNA, efficient transcription of poly[d(A-T)], were similar to those described for C RNA polymerases from other sources. The molecular structures of CI, CII and CIII enzymes were indistinguishable; the enzymes were composed of two high molecular polypeptides 158,000 and 138,000 and several smaller subunits 99,000, 80,000, 78,500, 64,500, 52,000, 44,000, 32,000 and 24,000. Transcriptional activities of the chromatographically distinct forms of C polymerases were the same. The C enzymes exhibited striking affinity for homologous native A-T enriched DNA; Km values showed the greater number of binding and initiation sites localized in this template; therefore, A-T pairs are considered to be starter points for the transcription process catalysed by class C RNA polymerases.
小牛胸腺组织中的依赖DNA的RNA聚合酶被溶解并纯化。在通过DEAE-纤维素或DEAE-葡聚糖凝胶色谱法获得的七种色谱不同形式的RNA聚合酶中，发现了三类酶C。其一般酶学性质，如对α-鹅膏蕈碱的中等敏感性、对二价阳离子的需求、对天然DNA的偏好、对聚[d(A-T)]的高效转录，与其他来源的C RNA聚合酶所描述的性质相似。CI、CII和CIII酶的分子结构无法区分；这些酶由两条高分子多肽158,000和138,000以及几个较小的亚基99,000、80,000、78,500、64,500、52,000、44,000、32,000和24,000组成。色谱上不同形式的C聚合酶的转录活性相同。C酶对同源的富含A-T的天然DNA表现出显著的亲和力；Km值表明该模板中存在更多的结合和起始位点；因此，A-T对被认为是C类RNA聚合酶催化的转录过程的起始点。
