[Mechanism of heavy metal ions on RNase activity from bovine pancreas].
This paper studied mechanism of Ce3+, Cd2+, Pb2+ on RNase activity from bovine pancreas. The results showed that the activity of RNase was enhanced under the treatment by Ce3+, Cd2+, Pb2+ at lower concentration (10-60 or 10-30 mumol.L-1), but was inhibited by Ce3+, Cd2+, Pb2+ at higher concentration (40 or 70 mumol.L-1 above), and the inhibition was in the order as Pb2+ > Cd2+ > Ce3+. The equilibrium dialysis demonstrates that RNase may have one Ca(2+)-binding site. The fluorescence titration showed that one molecule of RNase has one binding site for Ce3+, the association constant k for its low-affinity Ce(3+)-binding site is 1.22 x 10(8) L.mol-1. However, it can bind three Cd2+ or Pb2+ and the association causing constant k for its low-affinity Cd2+ or Pb(2+)-binding site is 1.8 x 10(8) L.mol-1, 2.01 x 10(8) L.mol-1, respectively, and caused the conformational changes of RNase.
Hong
Fa-shui
FS
Department of Biology Science, Suzhou University, Suzhou 215006, China.
Wang
Xue-feng
XF
Su
Guo-xing
GX
Pan
Xin-fa
XF
Shen
Song-dong
SD
D000818:Animals; D001665:Binding Sites; D002104:Cadmium / Q000737:chemistry; D002118:Calcium / Q000737:chemistry; D002417:Cattle; D002563:Cerium / Q000737:chemistry; D007854:Lead / Q000737:chemistry; D019216:Metals, Heavy / Q000737:chemistry*; D012259:Ribonuclease, Pancreatic / Q000737:chemistry*; D012260:Ribonucleases / Q000737:chemistry*
D019216:Metals, Heavy; D002104:Cadmium; D007854:Lead; D002563:Cerium; D012260:Ribonucleases; D012259:Ribonuclease, Pancreatic; D002118:Calcium