III Bioenergetics and Metabolism 13 Principle of Bioenergetics 14 Glycolysis and the Catabolism 15 The Citric Acid Cycle 16 Oxidation of Fatty Acid 17 Amino Acid Oxidation and the Production of Urea 18 Oxidative Phosphorylation and Photophosphrylation 19 Carbohydrate Biosynthesis 20 Lipid Synthesis 21 Biosynthesis of Amino Acids, Nucleotides, and Related Molecules 22 Integration and Hormonal Regulation of Mammalian Metabolism

Three major organizing principles of biosynthesis First, the pathway taken in the synthesis of a biomolecule is usually different from the pathway taken in its degradation. Second, corresponding anabolic and catabolic pathways are controlled by different regulatory enzymes. Third, energy-requiring biosynthetic processes are coupled to the energy-yielding breakdown of ATP in such a way that the overall process is essentially irreversible in vivo.

*** Gluconeogenesis *** Biosynthesis of Glycogen, Starch, Sucrose, and Other Carbohydrates *** Phototynthetic Carbohydrate Synthesis *** Regulation of Carbohydrate Metabolism in Planets

Gluconeogenesis; the metabolic formation of carbohydrates (glucose) from non-cabohydrate organic precursors in liver. In all mammals, The biosynthesis of glucose is an absolute necessity because the brain and nervous system, as well as the kidney medulla, testes, erythrocytes, and embryonic tissues, require glucose from the blood as their sole or major fuel source. In many plants, before photosynthesis, gluconeogenesis converts fats and proteins to glucose as sources of energy and biosynthetic precursors during germination.

Glyconeogenic Pathway

Conversion of Pyruvate into Phosphoenolpyruvate Requires a Bypass

First Bypass in Glyconeogenesis

Non-active active 丙酮酸羧化酶 PEP 羧激酶

Oxaloacetate transport by Malate-aspartate shuttle system

Conversion of Pyruvate into Phosphoenolpyruvate Requires a Bypass Alternative paths from pyruvate to phosphoenolpyruvate. The path that predominates depends upon the gluconeogenic precursor (lactate or pyruvate) and is determined by cytosolic requirements for NADH in gluconeogenesis

Conversion of Fructose-1,6-Bisphosphate into Fructose-6-Phosphate Is the Second Bypass Fructose-1,6-bisphosphate + H 2 O fructose-6-phosphate + Pi

Conversion of Glucose-6-Phosphate into Free Glucose Is the Third Bypass Glucose-6-phosphate + H 2 O glucose + Pi ΔG°' = kJ/mol

Gluconeogenesis Is Expensive

2Pyruvate +4ATP +2GTP +2NADH +4H 2 O glucose +4ADP +2GDP +6Pi +2NAD+ +2H + Glucose + 2ADP + 2Pi + 2NAD + 2 pyruvate + 2ATP + 2NADH + 2H + + 2H 2 O

Citric Acid Cycle Intermediates and Many Amino Acids Are Glucogenic

Futile Cycles in Carbohydrate Metabolism Consume ATP ATP + fructose-6-phosphate ADP + fructose-1,6-bisphosphate + H + Fructose-1,6-bisphosphate + H 2 O fructose-6-phosphate + Pi The sum of these two reactions is ATP + H 2 O ADP + Pi + H + + heat

东方臭松 南极冰盖 天山雪莲

Three Heat production in Organisms I II III

pyruvate dehydrogenase complex of glycolysis pyruvate carboxylase of gluconeogenesis. Gluconeogenesis and Glycolysis Are Reciprocally Regulated

The hormonal regulation of glycolysis and gluconeogenesis in liver is mediated by fructose-2,6- bisphosphate, an allosteric effector for the enzymes phosphofructokinase-1 (PFK-1 ， 磷酸果糖激酶 -1 ) and fructose-1,6-bisphosphatase (FBPase-1 ， 果糖 -1,6- 二磷酸酶 ).

Gluconeogenesis and Glycolysis Are Reciprocally Regulated

Gluconeogenesis Converts Fats and Proteins to Glucose in Germinating Seeds 乙醛酸循环体

*** Gluconeogenesis *** Biosynthesis of Glycogen, Starch, Sucrose, and Other Carbohydrates *** Phototynthetic Carbohydrate Synthesis *** Regulation of Carbohydrate Metabolism in Planets

1.UDP-glucose is the substrate for glycogen synthesis in animals and for sucrose synthesis in plants. 2.ATP-glucose is the substrate for starch synthesis in plants and Glycogen Synthesis in Bacteria.

Synthesis of NDP-Sugar

UDP-Glucose Is the Substrate for Glycogen Synthesis

糖原分支酶

UDP-Glucose Is the Substrate for Sucrose Synthesis in Plants

ADP-Glucose Is the Substrate for Starch Synthesis in Plants and Glycogen Synthesis in Bacteria

Role of UDP-glucuronate in detoxification 3- 羟苯并芘 UDP 葡糖醛酰基转移酶 苯并芘葡萄糖苷酸

*** Gluconeogenesis *** Biosynthesis of Glycogen, Starch, Sucrose, and Other Carbohydrates *** Photosynthetic Carbohydrate Synthesis *** Regulation of Carbohydrate Metabolism in Planets

CO2 was added into organic compounts. But, ---- Release soon

1.Biotin 2.Biotin Caboxylase 3.Biotin Carrier Protein 4.Transcarboxylase

Biosynthesis of palmitate

Carbon Dioxide Fixation Occurs in Three Stages 1.Fixation of CO 2 into 3-Phosphoglycerate （ 3- 磷酸甘油酸） 2.Conversion of 3-Phosphoglycerate to Glyceraldehyde-3-Phosphate （甘油醛 -3- 磷酸） 3.Regeneration of Ribulose-1,5-Bisphosphate （核酮糖 - 1,5- 二磷酸） from Triose Phosphates （丙糖磷酸）

Stage 1: Fixation of CO2 into 3- Phosphoglycerate; An important clue to the nature of the CO2 fixation Ribulose 1,5-bisphosphate + CO2 3-Phosphoglycerate Rubisco Rubisco: Ribulose 1,5-bisphosphate Carboxylase

Stage 1: Fixation of CO2 into 3-Phosphoglycerate; An important clue to the nature of the CO2 fixation 核酮糖 -1,5- 二磷酸烯二醇中间体 3- 磷酸甘油酸 碳负离子 2’- 羧基 -3- 酮 - D - 阿拉伯糖 -1,5- 二磷酸 （ β- 酮酸中间体） 水合物中间体

Ribulose1,5-bisphosphate carboxylase (rubisco). Eight large subunits (shown in gray and dark blue) Eight small subunits (white and shades of light blue

Stage 1: Fixation of CO2 into 3-Phosphoglycerate; An important clue to the nature of the CO2 fixation

Stage 2: Conversion o f 3-Phosphoglycerate to Glyceraldehyde-3-Phosphate 3-Phoshoglycerate 3-phosphoglycerate kinase 1,3-Bisphoglycerate glyceraldehyde 3-phosphate dehydrogenase Glyceraldehyde 3-phosphate Triose phosphate isomerase Dihydroxyaceton phosphate

Stage 3: Regeneration of Ribulose-1,5- Bisphosphate from Triose Phosphates 3 Glyceraldehyde 3-phosphate + 2 Dihydroxyaceton phosphate 3 Ribulose-1,5-Bisphosphate

Stage 3: Regeneration of Ribulose-1,5-Bisphosphate from Triose Phosphates

The ATP Synthease in of Mitochondria, Chloroplasts and Bacterium

A Transport System Exports Triose Phosphates and energy, and Imports Phosphate

*** Gluconeogenesis *** Biosynthesis of Glycogen, Starch, Sucrose, and Other Carbohydrates *** Phototynthetic Carbohydrate Synthesis *** Regulation of Carbohydrate Metabolism in Planets

The key enzymes are regulated by one or more of following mechanisms 1.Reduction of disulfide bonds by electrons flowing from photosystem I. 2.Changes in pH and Mg 2+ concentration that result from illumination. 3.Covertional allosteric regulation by one or more metabolic intermediate. 4.Covalent modification.

Certain Enzymes of the Calvin Cycle Are Indirectly Activated by Light 1.Ribulose-5-phosphate kinase 2.fructose-1,6-bisphosphatase 3.sedoheptulose-1,7-bisphosphatase 4.Glyceraldehyde 3-phosphate dehydrogenase They can exist in either of two forms, differing in the oxidation state of Cys residues essential to their catalytic activity.

Thioredoxin （硫氧还蛋白） donates electrons for the reduction of the disulfide bridges of these light- activated enzymes and is then reactivated in a disulfide- exchange reaction catalyzed by thioredoxin reductase. 硫氧还蛋白还原酶

Certain Enzymes of the Calvin Cycle Are Indirectly Activated by Light The light-induced transport of protons across the thylakoid membrane also makes the stromal compartment alkaline and is accompanied by a flow of Mg2+ out of the thylakoid compartment into the stroma.

Certain Enzymes of the Calvin Cycle Are Indirectly Activated by Light

Rubisco Is Subject to Both Positive and Negative Regulation Synthesis in dark

Photorespiration Results from Rubisco’s Oxygenase Activity RuBP carboxylase/oxygenase Rubisco is not absolutely specific for CO2 as a substrate; O2 competes with CO2 at the active site, and rubisco catalyzes the condensation of O 2 with ribulose-1,5- bisphosphate to form one molecule of 3- phosphoglycerate and one of phosphoglycolate

RuBP carboxylase/oxygenase is a event of molecular evolution. Photorespiration; (C3) the pathway that salvages the carbons from phosphoglycolate

RuBP carboxylase/oxygenase is a event of molecular evolution. Photorespiration; (C3) the pathway that salvages the carbons from phosphoglycolate

C3 plants; fix CO2 into a three-carbon product, 3- phosphoglycerate, C4 plants; Some Plants Have a Mechanism to Prevent Photorespiration. Most plants in the tropics, as well as temperate- zone crop plants native to the tropics, such as corn, sugar cane, and sorghum. The ultimate step of CO2 fixation into a three- carbon product, 3-phosphoglycerate, is preceded by several steps, one of which is a preliminary fixation of CO2 into a compound with four carbon atoms. These plants are referred to as C4 plants. C4 plants, 1) high photosynthetic rates, 2) high growth rates, 3) low photorespiration rates, 4) low rates of water loss, and 5) an unusual leaf structure.

Some Plants Have a Mechanism to Minimize Photorespiration 叶肉细胞 胞间连丝 维管束鞘细胞

High affinity for HCO3 and can fix CO2 more efficiently Lower O2 concentration, High CO2 concentration.

GT: Gigatons

1.One way to limit the increase in atmospheric CO2 would be to engineer plants or microorganisms with a greater capacity for sequesteing CO2? 2.A second approach to limiting the increase of atmospheric CO2 is 3.And third? 4.What is your idea?