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1、灰綠曲霉肛葡笱糖苷酶分離純化及性質(zhì)表明較低濃度SDS即可對BG活力有較強(qiáng)的抑制作用。以熒光發(fā)射光譜研究酶經(jīng)不同濃度鹽酸胍和SDS變性后的分子構(gòu)象變化，結(jié)果顯示，酶經(jīng)變性后，338nm熒光發(fā)射峰逐漸紅移，說明酶分子充分伸展，變性完全。比較酶經(jīng)鹽酸胍和SDS變性后的活力與構(gòu)象變化的關(guān)系，表明酶在鹽酸胍和SDS溶液中的失活均先于其去折疊的過程，這種活力喪失快于酶分子整體構(gòu)象變化的現(xiàn)象表明酶活性中心處于對變性劑較為敏感的區(qū)域。優(yōu)化灰綠曲霉纖維素酶水解稻草粉產(chǎn)糖條件發(fā)現(xiàn)，在100ml含3％稻草粉的酶解體系中發(fā)酵產(chǎn)糖最適條件為：溫度55℃，酶解體系pH5．0，酶液用量12ml。在此條件下，
2、發(fā)酵24h后，還原糖濃度為13．1mg／ml，稻草粉糖化率為39．1％。關(guān)鍵詞t灰綠曲霉p．葡萄糖苷酶分離純化酶學(xué)性質(zhì)糖化2灰綠曲霉p葡萄糖苷酶分離純化及性質(zhì)AbstractA13-1，4-glucosidase(BG)waspurifiedfromfermentationliquorofAspergillusgtaucusbyfollowingprocedures：ammoniumsulfateprecipitation，gelfiltrationonSephadexG·100，andhydrophobicchromatographyonPhenylSepharoseFast
3、Flow．ThespecificactivityonsalicinWasdeterminedtobe1747．4U／mg．ThemolecularweightofthisenzymeWasdeterminedtobe23．5kDaand92．5kDawithSDS—PAGEandgelfiltrationonSephadexG-100，respectively,indicatingthatBGisatetramer．TheenzymewasstableatthepHrangingfrom3．0to7．5，anditsmaximumactivitywasobtainedatpH3
4、．6．Theenzymaticactivitygraduallyincreasedintherangefrom40to600C，butasharpdecreaseoccurredat650C．ItWasstablebelow650C．EnzymatickineticsindicatedthatMichaelis—Mentencontant(‰)ofthehydrolysisforsalicinbyBGWas2．58mmol／L(pH3．6，60oC)．Chemicalmodificationshowedthattheenzymeactivitywasnotinhibitedby
5、mercaptoethanol(ME)，dithiothreitol(DTT)，p-chloromercuribenzoate(pCMB)，acetylacetone(ACAC)，andPhenyimethanesulfonylfluoride(PMSF)，suggestingthattheresiduesofdisulfidebond，mercapto，L-arginineguanidine，serinedeformitywerenotnecessaryfortheenzymeactivity．WhiletheresiduesofHis，Trp，LysandAsp／Gluwe
6、reessentialtotheactivesitesofBG．Fermentationproductsethonal，aceticacidandlaticacidshowednon—competitiveinhibitiontoBG．Theeffectsofseveralions011theenzymeactivityhadbeenresearched．Theresultsshowthat：CI‘、S042。、N03‘、Li+、Nd、K+、M92+、ca+、Ba2+andZn2+hadnoeffectsonBGactivity,itwasactivatedbyMn2+，F(xiàn)e2
7、+,whilestronglyinhibitedbyCu2+，ab2+，Cd2+andH92+．Theinactivationeffectsinionssolvents(Cu+，Pb2+，Cd2+，H礦)havebeenstudiedusingthekineticmethodofLineweaver-Burkplot．Cu2+，Pb2+，andCd2+showednon．competitiveinhibitiontoBGwhiletheinactivationoftheenzymeinH礦+
