(2)ATP합성 ATP합성효소의 전자현미경사진 및 모식도(그림10.14-15) 작은 미토콘드리아입자(SMP), 초음파분해, 안에서밖으로 돌출 F1, F0단위 (3)산화적 인산화의 제어 -P/O비율(각각의 산소원자가 물분자로 환원되는데 소모되는 Pi몰의 수 -ADP에 의한 호기성 호흡의 제어를 호흡통제라함 -ATP-ADP전위체(translocator)와 인산운반체(phosphate carrier)같은 수송단백질이 미토콘드리아 내 ADP, ATP의 농도를 조절(그림10.16)

Section 10.2: Oxidative Phosphorylation ATP Synthesis Continued F1 unit has five subunits: a3, b3, g, d, and e F0 unit has three subunits: a, b2, and c12 F0 motor converts the proton motive force into the rotational force of the central shaft (e and g subunits) that, in turn, drives ATP synthesis Figure 10.14 The ATP Synthase From Escherichia coli From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Section 10.2: Oxidative Phosphorylation ATP Synthesis Continued b subunits of the ATP synthase have three conformations: open (O), tight (T), and loose (L) Steps: 1. ADP and Pi bind to L site; rotation converts it to T conformation 2. ATP synthesized 3. Rotation converts T site to O site, releasing ATP Figure 10.15 ATP Synthesis Model From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Section 10.2: Oxidative Phosphorylation Control of Oxidative Phosphorylation Activated when ADP (respiratory control) and Pi concentrations are high Inhibited when ATP concentrations are high Figure 10.16 The ADP-ATP Translocator and the Phosphate Translocase From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Section 10.2: Oxidative Phosphorylation Control of Oxidative Phosphorylation Cont. Amounts of ATP and ADP in mitochondria are controlled by the ADP-ATP translocator Amount of H2PO4- is controlled by phosphate carrier (H2PO4-/H+ symporter) Figure 10.16 The ADP-ATP Translocator and the Phosphate Translocase From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

(4)글루코오스의 완전산화 -ATP생성원(표10.2) -NADH는 미토콘드리아내막을 통과못함(해당과정 시 생성분의 이동):글리세롤-인산 왕복수송계(그림10.17a)와 말산-아스파르트산 왕복수송계(그림10.17b)을 발전 (5)짝풀린 전자수송(탈공역 전자수송과 열생산) -신생아, 동면동물 및 추운지역에 사는 동물은 대사에 의해 열생산 -갈색, 많은 미토콘드리아로 -갈색지방세포의 미토콘드리아 내막속의 단백질 중 10%는 탈공역단백질(uncoupling protein, UCP)로, 전자수송사슬로 생산된 에너지를 ATP생산하는데 사용치 않고 열생산에 사용

Section 10.2: Oxidative Phosphorylation Figure 10.17a Shuttle Mechanisms That Transfer Electrons from Cytoplasmic NADH to the Respiratory Chain The Complete Oxidation of Glucose Two mechanisms to move electrons from cytoplasmic NADH, derived from glycolysis, into the mitochondrial ETC are glycerol phosphate shuttle and malate-aspartate shuttle From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Section 10.2: Oxidative Phosphorylation Figure 10.17a Shuttle Mechanisms That Transfer Electrons from Cytoplasmic NADH to the Respiratory Chain The Complete Oxidation of Glucose Continued The glycerol phosphate shuttle uses cytoplasmic NADH (glycolytic pathway) to reduce DHAP into glycerol-3-phosphate, which can enter the intermembrane space From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Section 10.2: Oxidative Phosphorylation The Complete Oxidation of Glucose Continued The malate-aspartate shuttle is used to transfer electrons from cytoplasmic NADH (glycolytic pathway) to the mitochondrial ETC This is the more efficient of the two mechanisms Figure 10.17b Shuttle Mechanisms That Transfer Electrons from Cytoplasmic NADH to the Respiratory Chain From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Section 10.2: Oxidative Phosphorylation The Complete Oxidation of Glucose Continued Cytoplasmic NADH reduces oxaloacetate to malate, which is transported to the matrix Malate is reoxidized to produce NADH Figure 10.17 Shuttle Mechanisms That Transfer Electrons from Cytoplasmic NADH to the Respiratory Chain From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Section 10.2: Oxidative Phosphorylation From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

10.3 산소, 세포기능 및 산화적 스트레스 -반응성 산소종(reactive oxygen species, ROS) -항산화제(antioxidant) -산화적스트레스 -산소를 소모하는 반응과정인 호흡파열(respiratory burst)시 ROS생성, 세포파괴 (1)반응성 산소종 -라디컬: 하나 혹은 그 이상의 쌍을 이루지 않는 전자를 포함한 원자 -전자가 전자수송회로를 새어나와 산소와 결합하여 ROS형성, 초과산화물라디칼은 대부분 복합체III의 Q회로 및 플라보단백질 복합체I에서 생산(그림10.18) 2H+ + 2O2- → O2 + H2O2 Fe2+ + H2O2 → Fe3+ + •OH + OH- -히드록시 라디칼(•OH )은 자가촉매 라디칼 연쇄반응을 하여 위험(그림10.19): 지질의 과산화반응은 라디칼절단반응으로 -단일항 산소(1O2): 2O2- + 2H+ → H2O2 + 1O2 2ROOH → 2ROH + 1O2 -ROS는 생체이물(xenobiotic)대사나 백혈구의 호흡파열로도 형성(그림10.20) ;1)세균의 파고솜내 이입, 리소좀과결합, 초과산화물 라디칼형성, SOD에 의해 H2O2형성, 미엘로과산화효소에 의해 살균물질인 하이포할로겐 화합물형성. 2) Fe존재 하에 •OH 와 1O2형성

All living processes take place within a redox environment Section 10.3: Oxygen , Cell Function, and Oxidative Stress All living processes take place within a redox environment Redox state is regulated within a narrow range because of redox-sensitive nature of many pathways Important linked redox pairs (NAD(P)H/NAD(P)+ and GSH/GSSG) help maintain redox conditions GSH (glutathione) is a key cellular-reducing agent From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Antioxidants interact with ROS to mitigate damage Section 10.3: Oxygen , Cell Function, and Oxidative Stress Oxygen usage comes with the danger of forming reactive oxygen species (ROS) Some ROS act as signaling molecules Antioxidants interact with ROS to mitigate damage Under certain conditions, antioxidant mechanisms are overwhelmed, leading to oxidative stress Oxidative damage has been linked to 100 human diseases From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Reactive Oxygen Species Section 10.3: Oxygen , Cell Function, and Oxidative Stress Figure 10.18 Overview of Oxidative Phosphorylation and ROS Formation in the Mitochondrion Reactive Oxygen Species Properties of oxygen related to its structure Diatomic oxygen is a diradical, meaning it has two unpaired electrons From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Reactive Oxygen Species Continued Section 10.3: Oxygen , Cell Function, and Oxidative Stress Figure 10.18 Overview of Oxidative Phosphorylation and ROS Formation in the Mitochondrion Reactive Oxygen Species Continued Oxygen can only accept one electron at a time Electrons can leak out of the ETC and interact with O2 From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Types of reactive oxygen species: Section 10.3: Oxygen , Cell Function, and Oxidative Stress Types of reactive oxygen species: First created is superoxide radical (O2●-), which acts as a nucleophile O2●- can react with itself to form hydrogen peroxide H2O2 H2O2 can react with Fe2+ to form hydroxyl radical (●OH), which can initiate autocatalytic radical chain reaction Figure 10.19 Radical Chain Reaction From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Section 10.3: Oxygen , Cell Function, and Oxidative Stress Singlet oxygen (1O2) formed from H2O2 or superoxide can be damaging to aromatics and conjugated alkenes Figure 10.19 Radical Chain Reaction From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

There are also reactive nitrogen species (RNS) Section 10.3: Oxygen , Cell Function, and Oxidative Stress There are also reactive nitrogen species (RNS) Nitric oxide, nitrogen dioxide, and peroxynitrite are important examples Nitric oxide (●NO) is an important signaling molecule Physiological functions of NO include blood pressure regulation, inhibition of blood clotting, and destruction of foreign cells by macrophages From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Section 10.3: Oxygen , Cell Function, and Oxidative Stress Figure 10.20 The Respiratory Burst From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Reactive oxygen species also generated for the respiratory burst Section 10.3: Oxygen , Cell Function, and Oxidative Stress Reactive oxygen species also generated for the respiratory burst Macrophages and neutrophils actively make large quantities of ROS Use ROS in order to destroy microorganisms and damaged cells From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

(2)항산화제의 효소계 -초과산화물 불균형효소(SOD): 초과산화물 라디칼에서 H2O2와 O2형성을 촉매, Cu-Zn 동위효소, Mn을 함유한 동위효소. -카탈라아제(catalase):헴함유 효소로 H2O2를 환원 -글루타티온 과산화효소(glutathione peroxidase): Se을 함유하며 GSH를 이용하여 다양한 물질을 환원, H2O2의 환원 및 유기과산화물을 알코올로 전환 -글루타티온 과산화효소를 보조하는 여러 효소(그림10.21), 이 반응의 NADPH는 오탄당인산회로에 의해 공급 -티오레독신 중심계(그림10.22) (3) 항산화제분자 -라디칼 등 ROS를 제거함 -GSH, α-토코페롤(비라민E, 페놀 항산화제), 아스코르브산(비타민C), β-카로틴[레티놀(비타민A)의 전구물질] 등(그림10.23) -아스코르브산에 의한 α-토코페롤의 재생(그림10.24) * 심근경색: 심허열 및 재주입

Antioxidant Enzyme Systems Section 10.3: Oxygen , Cell Function, and Oxidative Stress Antioxidant Enzyme Systems To protect against oxidative stress, living organisms have developed several antioxidant defense mechanisms Major enzymatic defenses are provided by four enzymes: superoxide dismutase, glutathione peroxidase, peroxiredoxin, and catalase Superoxide dismutase forms H2O2 and O2 from superoxide radical Catalase forms H2O and O2 from H2O2 From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Antioxidant Enzyme Systems Continued Section 10.3: Oxygen , Cell Function, and Oxidative Stress Figure 10.21 The Glutathione-Centered System Antioxidant Enzyme Systems Continued Glutathione peroxidase uses the reducing agent GSH to control peroxide levels Reduces H2O2 to form water and transforms organic peroxides to alcohols Glutathione reductase is also an important enzyme in the glutathione system From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Antioxidant Enzyme Systems Continued Section 10.3: Oxygen , Cell Function, and Oxidative Stress Figure 10.22 The Thioredoxin-Centered System Antioxidant Enzyme Systems Continued Peroxiredoxins (PRX) are a class of enzymes that detoxify peroxides Uses thiol-containing peptides like thioredoxin Thioredoxin is involved in redox reactions mediated by the peroxiredoxin/thioreductase system From McKee and McKee, Biochemistry, 5th Edition, © 2011 Oxford University Press

Antioxidant Molecules Section 10.3: Oxygen , Cell Function, and Oxidative Stress Figure 10.23 Selected Antioxidant Molecules Antioxidant Molecules Organisms use antioxidant molecules to protect themselves from radicals a-Tocopherol (vitamin E) is a potent, lipid-soluble radical scavenger From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Antioxidant Molecules Continued Section 10.3: Oxygen , Cell Function, and Oxidative Stress Figure 10.23 Selected Antioxidant Molecules Antioxidant Molecules Continued b-carotene, a carotenoid, is a precursor of vitamin A (retinol): a potent, lipid-soluble radical scavenger in membranes From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press

Antioxidant Molecules Continued Section 10.3: Oxygen , Cell Function, and Oxidative Stress Figure 10.24 Regeneration of a-Tocopherol by L-Ascorbate Antioxidant Molecules Continued Ascorbate protects membranes through two mechanisms: scavenging a variety of ROS in aqueous environments and enhancing the activity of a-tocopherol From McKee and McKee, Biochemistry, International Fifth Edition, © 2012 by Oxford University Press