Acta Chimica Sinica ›› 2003, Vol. 61 ›› Issue (1): 117-121. Previous Articles     Next Articles

Original Articles

Pb^2+对核糖核酸酶活性及其结构的影响

洪法水;王玲;吴康;王雪峰;陶冶   

  1. 苏州大学生命科学院,苏州(215006);苏州大学图书馆,苏州(215006);中国科 学院高能物理研究所.北京(100039)
  • 发布日期:2003-01-15

Effect of Pb~(2+) on RNase Activity and Its Structure

Hong FaShui;Wang Ling;Wu Kang;Wang XueFeng;Tao Ye   

  1. College of Life Sciences,Suzhou(215006);Library, Suzhou University, Suzhou4e215006;Synchrotron Radiation Laboratory, Institute of High Energy Physics, The Chinese Academy of Sciences.Beijing 100039
  • Published:2003-01-15

Activity of RNase from porcine pancreas was enhanced by treatment with Pb~(2+) at low concentration (0.17×10~(-2)~0.6×10~(-2)μmol/L) but was indibited by Pb~(2+) at high concentration (over 0.85×10~(-2) μmol/L). Pb~(2+) at the high concentration could competitively displace Ca~(2+) from RNase and the fluorescence titration showed that one molecule of RNase had three binding sites for Pb~(2+), the association constant κ_(siv for its low-affinity Pb~(2+) -binding site was 6.03×10~6(mol/L)~(-1). The extended X-ray absorption fine structure (EXAFS) spectrum demonstrated that Pb~(2+) coordinated nitrogen or oxygen atoms of the active site of RNase or other amino acid residue of RNase, Pb-N (or O) bond length was 0.242nm and o.312nm, and coordination number was 2, respectively. The secondary structure of RNase was greatly damaged by Pb~(2+) at high concentration resulting in the decrease of α-helix, β-sheet andβ-turn contents and the increase of random coil contents.

Key words: RIBONUCLEIC ACID, ACTIVITY, COORDINATION, ENVIRONMENT, ENZYME, STRUCTURE, LEAD, SPECTROGRAPHIC ANALYSIS, HEAVY METAL POLLUTION, PHYSIOLOGY

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