Laccases　(EC　1.10.3.2)　have　important　industrial　values　in　areas　such　as　bioremediation,　but　they　are　often　inactivated　by　heavy　metal　ions　in　real　applications.　In　this　report,　laccase　from　a　high　laccase-producing　Cerrena　sp.　HYB07　presented　resistance　to　many　metal　ions　except　for　Ag+,　Hg2+,　Li+　and　Pb2+,　the　inhibition　of　which　on　the　laccase　were　all　reversible.　The　presence　of　these　four　cations　decreased　Remazol　Brilliant　Blue　R　decolorization　efficiencies　catalyzed　by　the　laccase,　and　the　mediator　2,2＇-azino-bis(3-ethylbenzothiazoline-6-sulfonic　acid)　could　restore　the　decolorization　efficiency　in　spite　of　Hg2+　inhibition.　Hg2+　had　the　lowest　IC50　value　(0.17　mM)　on　the　laccase　activity,　followed　by　Ag+,　Li+　and　Pb2+.　The　inhibition　type　on　laccase　activity　was　competitive　for　Pb2+,　noncompetitive　for　Hg2+,　and　mixed　type　for　Ag+　and　Li+.　The　inhibition　kinetic　model　of　Hg2+　on　laccase　activity　was　established　by　using　the　kinetic　method　of　substrate　reaction.　The　microscopic　forward　inhibition　rate　constant　(k(+0))　of　Hg(2+)was　3.26　x　10(-2)/s　and　the　microscopic　reverse　inhibition　rate　constant　(k(-0))　was　1.36　x　10(-3)/s,　indicating　the　laccase　would　be　completely　inhibited　when　Hg2+　concentration　was　sufficiently　high　because　k(+0)　was　much　larger　than　k(-0).　Furthermore,　Hg2+　reduced　thermal　and　pH　stability　of　the　laccase.　Fluorescence　emission　spectra　demonstrated　that　Hg2+　had　one　binding　site　per　laccase　protein　regardless　of　pH,　and　the　binding　was　stronger　at　pH　6.0　than　that　at　pH　5.0　or　9.0,　in　accordance　with　the　lowest　stability　of　the　enzyme　at　pH　6.0　with　Hg2+.　Dynamic　simulation　was　performed　to　identify　the　binding　sites　of　each　ion　on　the　Lac7　protein.　(C)　2018　Taiwan　Institute　of　Chemical　Engineers.　Published　by　Elsevier　B.V.　All　rights　reserved.