22-2 課堂整理 第二十六組 B97310029 黃伯仕 B97310032 王鈺婷 B97310048 朱得榮

心智圖 α-amylase Digestion Glycogen α -(1,6) glucosidase debranching enzyme phosphorylysis Glycogen phosphorylase UDP glucose synthesis Glycogenin Branching enzyme First phases Glucose 6-phosphate dehydrogenase gluconolactonase Pentose phosphate pathway ( PPP) 6-phosphogluconate dehydrogenase Second phase Transaldolase Transketolase

Digestion of Glycogen

Glycogen phosphorylase 可以催化α -(1,4)鍵水解而釋放出glucose-1-phosphate

Glycogenin Branching enzyme: 讓第一個葡萄糖接上 Tyr-OH攻擊UDP glucose Amylo-(1,4->1,6)transglycosylase (transfer 6-, 7- residues) glucokinase Glucose +ATP G6P +ADP G6P G1P

Glycogen synthase

Glycogen synthase 在Glycogen synthase II 受到Insulin 作用下，利用活化protein phosphatase 來把Pi去除，使glycogen synthase II轉成glycogen synthase I ，把glucose合成glycogen 。 相對的glucagon 把glycogen synthase I 轉成 glycogen synthase II 接上Pi，不利glycogen 的生成。

Pentose phosphate pathway G6P dehydrogenase(缺乏會得蠶豆症) 6-phosphogluconate dehydogenase 在氧化項的步驟中，主要藉由電子本身的轉移來形成NADPH和核糖，完成體內一些生合成反應。 在還原項的步驟中，主要藉著酵素的作用下把G-6-P再次還原成G-6-P重複使用。

PPP的還原步驟 G6P G6P ½ G6P

PPP氧化步驟 藉由產生NADPH和 Ribose-5-phosphate 來完成體內生合成反 應，如核苷酸的形成 和脂肪酸的合成或 是維持紅血球膜的完 整性等。 O2+e- O2 . O2.+O2. H2O2 H2O2+2GSH GS-SG+ H2O+ ½ O2 GS-SG+NADPH 2GSH+ NADP+ NADP+ NADPH SOD Glutathione peroxidase Glutathione reductase PPP

glycogen Glycogen synthesis 在glucose的代謝步驟中可分成三個命運，主要的中樞原料都是由Glucose-6-phosphate來負責的，其調控原則是由體內的生理需求來維持一定平衡，用來提供給細胞必要的合成或是分解反應等。

1. Muscle glycogen phosphorylase?(E) A. catalyzes the degration of glycogen by hydrolysis of glycosidic bond. B. catalyzes phosphorolysis of the (a1-6 ) bonds at the branch points of glycogen. C. removes glucose residues from the reducing ends of the glycogen chain. D. degrades glycogen to form glucose-6-phosphate. E. exists in an active (a) form and an inactive (b) form that is allosterically regulated by AMP. A.該為磷解反應而非水解 B.應該為a1-4 而非a1-6 C.應該為非還端開始移除而非還原端 D.分解肝醣的產物為glucose-1-phosphate而非glucose-6-phosphate.  

2. In a tissue that metabolizes glucose via the pentose phosphate pathway,C-1 of glucose would be expected to end up principally in?(A) A. carbon dioxide. B. glycogen. C. phosphoglycerate. D. pyruvate. E. ribulose 5-phosphate. 在PPP路徑中,第一步驟glucose-6-phosphate轉成6-phosphogluconate.第二步驟6-phosphogluconate轉成ribulose-5-phosphate時會把C-1碳以CO2的形式放出。

3. Breakdown of glycogen requires following enzymes except:(D) A. glycogen phosphorylase. B. glucantransferase. C. debranching enzyme. D. glycogen phosphatase.   Glycogen的代謝由細胞經過訊號因子的接收後,經過了幾步驟後 活化glycogen phosphorylase把glycogen直鏈部分分解成glucose-1-phosphate,分支的部分由debranching enzyme這個酵素包含glucantransferase和α -(1,6) glucosidase把分支的glycogen分解成glucose。 

4. Glycogen biosynthesis is the conversion of glucose to glycogen via:(D) A. G-1-P. B. G-6-P. C. G-1-P first and then G-6-P. D. G-6-P first and then G-1-P. 要把glucose轉成glycogen的話要先把glucose轉成G-6-P後,G-6-P轉成G-1-P,再把G-1-P轉成UDP-glucose後,直接並到glycogen的非還原端。

5. Which of the following statements about the pentose phosphate pathway is correct?(E) A. It generates 36 moles ATP per mole of glucose consumed. B. It generates 6 moles of CO2 for each mole of glucose consumed. C. It is a reductive pathway ; it consumes NADH. D. It is present in plant , but no on animals. E. It provides precursors for the synthesis of nucleotides. PPP路徑主要是用來生合成的步驟反應,不是用來產生能量的,所以所以不是用來生產能量沒有ATP的產生,而是2NADPH和CO2的生成，而PPP路徑中有氧化項和還原項兩部份，對於任何生物而言都是非常重要的，所以植物和動物都有PPP代謝路徑。

6. The main function of the pentose phosphate pathway is to:(E) A. give the cell an alternative pathway should glycolysis fail. B. provide a mechanism for the utilization of the carbon skeletons of excess amino acids. C. supply energy. D. supply NADH. E. supply pentose and NADPH.   PPP路徑中第一步驟glucose-6-phosphate轉成6-phosphogluconate時放出NADPH第二步驟6-phosphogluconate轉成ribulose-5-phosphate時放出CO2和NADPH,接著產物ribulose-5phosphate會轉成核苷酸的原料,另外NADPH會當成生合成的輔酶。