l-malate dehydrogenase in the development of the sea urchin Strongylocentrotus purpuratus☆

[摘要] l-Malatedehydrogenase(l-malate:NADoxidoreductaseEC1.1.1.37)oftheseaurchinStrongylocentrotuspurpuratusoccursintwoforms.Oneformisshowntobelocalizedinmitochondriaofthisspecies.Theotherformoccursexclusivelyinthecytoplasmandappearsasasupernatantenzyme.ThesetwoenzymesoftheseaurchinwereseparatedandpartiallypurifiedbyammoniumsulfatefractionationandDEAE-cellulosechromatography.Ofthetwo,thesupernatantenzymeiselutedfirstfromthechromatographiccolumnandmigratesmoreslowlytowardtheanodeindiscelectrophoresis.Catalyticactivitiesofbothenzymesweredeterminedwithvaryingconcentrationofsubstrates.Substrateinhibitionoccurredwiththesupernatantenzymeathighconcentrationofmalateandwiththemitochondrialenzymeathighconcentrationofoxaloacetate.Thesesubstrate-activityrelationshipsaresimilartothoseofcorrespondingenzymesofmanyotheranimals.Duringdevelopment,thetotalenzymeactivityinthehomogenateincreasesthreefoldatayoungpluteusstagefromtheleveloftheactivityintheunfertilizedeggs,mostoftheincreaseoccurringafterhatching.Onlytwoisozymeswerefoundintheeggsandembryos,andtheincreaseintheactivityoccursequallyinbothsupernatantandmitochondrialenzymes.Theincreasedoesnotappeartobeduetoareleasefrominhibitionbyasolubleinhibitorintheunfertilizedeggs.Electrophoreticmobilitiesofisozymesofthestrongylocentrotids,S.purpuratusandS.droebachiensisandofDendrasterexcentricusaresufficientlydifferenttobeofdiagnosticvalueindifferentiatingspeciesoriginsoftheenzymes.Hybridembryoswereproducedbycrossingthegametesbetweenthetwospecies.Onlytheenzymesofthematernalspecieswerefoundintheblockedhybridembryos.

[学科分类] 生物科学（综合）