A　superoxide　dismutase　(SOD)　was　purified　from　seeds　of　the　Chinese　black　soybean(Glycine　max　cv).　The　purification　procedure　comprised　ammonium　sulfate　precipitation,　ion-exchange　chromatography　on　CM-Sephadex　C-50,　affinity　chromatography　on　Affi-gel　blue　gel　and　HP　LC　on　DEAE　650-C.　The　final　enzyme　was　purified　15.40　fold　with　a　specific　activity　of　4619.3　U/mg　protein　and　a　recovery　of　enzyme　was　29.41%　from　(NH4)(2)SO4　precipitation.　The　SDS-PAGE　of　the　purified　protein　exhibited　a　molecular　mass　of　31.0　kDa　and　could　be　depolymerized　spontaneously　to　a　band　at　about　14.5　kDa　in　non-reducing　conditions,　and　a　diffusion　band　at　about　15.5　kDa　in　reducing　conditions,　indicating　a　double-strand　protein　with　intra-molecular　disulfide　bridges.　The　isoelectric　point　was　determined　to　be　5.6,　indicating　it＇s　an　acidic　protein.　The　enzyme　is　a　type　of　copper　plus　zinc　superoxide　dismutase　(Cu,　Zn-SOD)　because　it　was　greatly　inhibited　by　hydrogen　peroxide,　insensitive　to　chloroform-ethanol,　and　the　maximum　ultraviolet　absorbance　was　found　to　be　266　nm.　Thermostability　experiments　showed　that　the　activity　of　the　purified　enzyme　was　stable　after　exposure　to　temperatures　below　50　degrees　C,　and　the　activity　could　be　well　maintained　between　pH　6.0　and　8.0.　Moreover,　the　SOD　exerted　an　obvious　protective　effect　against　oxidative　stress　of　UVC　radiation　in　normal　human　liver　cell　strain　L-02　cells.　(C)　2011　Elsevier　Ltd.　All　rights　reserved.