最新ch3糖酵解和己糖的分解教学讲义PPT.ppt

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1、ch3糖酵解和己糖的分解Chapter3Glycolysisandcatabolismofhexoses糖酵解和己糖的分解代谢（糖代谢Ⅰ）3.1糖代谢概述3.2糖的消化、吸收和运输3.3糖酵解途径和已糖的分解代谢3.4戊糖磷酸途径3.2糖的消化、吸收和运输淀粉的消化α-amylaseα-glucosidaseα-dextrinase二糖的消化乳糖不耐受综合症（Lactoseintolerancesyndrome）有些成年人由于乳糖酶（Lactasedeficiency）缺乏，在食用牛奶后乳糖不能在小肠内完全消化吸收，进入大肠后由细菌转化为有害物质，引起腹胀、

2、腹泻等症状。糖的吸收糖的吸收是以单糖形式通过肠壁细胞吸收进入血液的过程，吸收的部位是小肠上段。糖的运输小肠内主要是Na+－单糖协同运输。由小肠上皮细胞进入进入血液通过促进扩散。（见物质运输）Glucosetransportinintestinalepithelialcells3.3糖酵解和已糖的分解代谢（GlycolysisandCatabolismofHexoses)Glycolysis,fromtheGreekglykysmeaning“sweet”,andlysismeaning“splitting”.糖酵解途径—最早被阐明的代谢途径TheDevelop

3、mentofBiochemistryandtheDelineationofGlycolysisWentHandbyHand1897,HansBuchnerandEduardBuchner(Germany),accidentalobservation:sucrose(asapreservative)wasrapidlyfermentedintoalcoholbycell-freeyeastextract.Theacceptedviewthatfermentationisinextricablytiedtolivingcells(i.e.,thevitalisti

4、cdogma)wasshakenandBiochemistrywasborn:Metabolismbecamechemistry!1900s,ArthurHardenandWilliamYoungPiisneededforyeastjuicetofermentglucose,ahexosediphosphate(fructose1,6-bisphosphate)wasisolated.1900s,ArthurHardenandWilliamYoung(GreatBritain)separatedtheyeastjuiceintotwofractions:one

5、heat-labile,nondialyzablezymase(enzymes)andtheotherheat-stable,dialyzablecozymase(metalions,ATP,ADP,NAD+).1910s-1930s,GustavEmbdenandOttoMeyerhof(Germany),studiedmuscleanditsextracts:Reconstructedallthetransformationstepsfromglycogentolacticacidinvitro;revealedthatmanyreactionsoflac

6、ticacid(muscle)andalcohol(yeast)fermentationswerethesame!DiscoveredthatlacticacidisreconvertedtocarbohydrateinthepresenceofO2(gluconeogenesis);observedthatsomephosphorylatedcompoundsareenergy-rich.(GlycolysiswasalsoknownasEmbden-Meyerhofpathway,EMP).Thewholepathwayofglycolysis(Gluco

7、setopyruvate)waselucidatedbythe1940s.3.3.1糖酵解途径糖酵解：葡萄糖分解为丙酮酸并伴随着生成ATP的过程。存在于所有生物。在真核细胞中，其反应部位在胞液中。Glucose2Pyruvate2ATP糖酵解概况preparatoryphasepayoffphaseReleasesenergy糖酵解反应过程糖酵解反应过程己糖激酶GrouptransferIrreversibleincells已糖激酶（hexokinase）的作用机制：ATP以Mg2+－ATP复合物参与反应。Substrate-inducedcleftclosi

8、ngisageneralfeature