Enzyme (Part 1)
Enzyme (Part 1)
KeyPrinciples[kaetallst]Enzymes are powerful biological catalystsEnzymes exhibit a very high degree of specificityEnzymatic reactions occur in specialized pockets calledactivesites.Two concepts explain the catalytic power of enzymes.Many enzymes are regulated
Key Principles Enzymes are powerful biological catalysts. Enzymes exhibit a very high degree of specificity. Enzymatic reactions occur in specialized pockets called active sites. Two concepts explain the catalytic power of enzymes. Many enzymes are regulated. ['kætəlɪst]
EnzymesIn 1897,Eduard Buchner:- demonstrated cell-free yeast extracts could fermentsugar to alcohol- showed fermentation was promoted by moleculesthat continued to function when removed from cells
Enzymes In 1897, Eduard Buchner: - demonstrated cell-free yeast extracts could ferment sugar to alcohol - showed fermentation was promoted by molecules that continued to function when removed from cells
Mostenzymes areproteinsCatalytic activity depends on the integrity of the nativeproteinconformationMolecular weight =ranges from 12,000 to over 1 millionSome enzymes require additional chemical components- cofactor: 1+inorganic ions,such as Fe2+, Mg2+, Mn2+, and Zn2+- coenzyme = complex organic or metalloorganic moleculethat act as transient carriers of specific functional groups
Most enzymes are proteins Catalytic activity depends on the integrity of the native protein conformation Molecular weight = ranges from 12,000 to over 1 million Some enzymes require additional chemical components: - cofactor : 1+ inorganic ions, such as Fe2+, Mg2+, Mn2+, and Zn2+ - coenzyme = complex organic or metalloorganic molecule that act as transient carriers of specific functional groups
Coenzymes as Transient CarriersofAtomsorFunctionalGroupsTable 6-2 Some Coenzymes That Serve as Transient Carriers ofSpecific Atoms or Functional GroupsExamples of chemicalDietaryprecursor inCoenzymegroupstransferredmammalsCOBiocytinBiotin (vitamin B.)CoenzymeAAcyl groupsPantothenicacid (vitamin[paenta"Aenik]泛酸B5)and othercompounds5'-Deoxyadenosylcobalamin (coenzyme B,2)Vitamin Br2H atoms and alkyl groups[raibaflevin]核黄素Flavin adeninedinucleotideElectronsRiboflavin (vitamin B.)LipoateElectrons and acyl groupsNot required in diet[lr'paot]硫辛酸NicotinamideadeninedinucleotideHydride ion (H-)Nicotinic acid (niacin,[.nika"tinik]烟碱的vitamin B,)[.piri'dpksi:n]吡哆醇Pyridoxal phosphateAminogroupsPyridoxine (vitamin Ba)[“fauleit]叶酸TetrahydrofolateOne-carbongroupsFolate (vitamin B,)Thiamine pyrophosphateAldehydesThiamine (vitamin B,)["Saramin]硫胺素
[pæntə ‘ θenɪk ]泛酸 [ ˌraɪbə‘flevɪn ] 核黄素 [ ˌnɪkə‘tɪnɪk ] 烟碱 的 [ˌpɪrɪˈdɒksiːn ] 吡哆 醇 [‘fəʊleɪt ]叶酸 [‘θaɪəmɪn] 硫胺素 [lɪ‘pəʊt] 硫辛酸