title: [Mechanism of heavy metal ions on RNase activity from bovine pancreas].
abstract: 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.
authors.affiliation: Department of Biology Science, Suzhou University, Suzhou 215006, China.
authors.forename: Fa-shui
authors.initials: FS
authors.lastname: Hong
authors.forename: Xue-feng
authors.initials: XF
authors.lastname: Wang
authors.forename: Guo-xing
authors.initials: GX
authors.lastname: Su
authors.forename: Xin-fa
authors.initials: XF
authors.lastname: Pan
authors.forename: Song-dong
authors.initials: SD
authors.lastname: Shen
mesh_terms: 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*
chemical_list: D019216:Metals, Heavy; D002104:Cadmium; D007854:Lead; D002563:Cerium; D012260:Ribonucleases; D012259:Ribonuclease, Pancreatic; D002118:Calcium