Class 19

Glycolysis Read Lehninger 14.1-14.2

pages 528 - 546

Objectives

Describe the importance of glycolysis to living systems Memorize the steps of glycolysis Identify which steps require and input of energy and which produce energy Explain the reaction mechanism of key enzymes Understand the chemical logic of glycolysis

Glyco-lysis: hydrolysis of sugar

Glycolysis

Glucose + 2ADP + 2Pi + 2NAD+ 2pyruvate + 2ATP + 2NADH + 2H+ = 85/

Glucose + 602 6CO2 + 6H2O = 2870/

Glycolysis

Hexokinase

= 16.7/

Phosphohexoseisomerase

= 1.7/

Phosphofructokinase-1

= 14.2/

Aldolase

= 23.8/

Aldolase intermeadiate

Triose phosphate isomerase

Glyceraldehyde-3-phosphate dehydrogenase

Glyceraldehyde-3-phosphate dehydrogenase

Phosphoglycerate kinase

G3P + ADP + Pi + NAD+ 3PG + ATP + NADH + H+ = 12.2/

Phosphoglycerate kinase

Phosphoglycerate mutase

(bisphosphoglycerate mutase)

(2,3-bisphosphoglycerate)

Enolase

Pyruvate kinase

Chemical logic of glycolysis

Chemical logic of glycolysis

Invest energy to split glucose into two high energy compounds Isomerization of glucose to fructose permits equal splitting to two 3-carbon aldehydes Oxidize aldehyde to acid and generate a high-energy, bisphospho compound Extract energy from bisphospho compounds by rearrangement and transfer of phospho groups to ADP

Energetics of glycolysis Enzyme Yield G G [product] uM

Hexokinase -1 ATP -16.7 -33.5 [G6P] 25

Phosphoglucoseisomerase +1.7 -2.5 [F6] 5.4

Phosphofructokinase-1 -1 ATP -14.2 -22.2 [F1,6P] 4.6

Aldolase +23.9 -1.3 [DHAP] 4.9

Triose phosphate isomerase +7.6 0 [G3P] 2.6

Glyceraldehyde-3-phosphate dehydrogenase

+2 NADH +6.3 (+12.6) -1.7 (-3.4) n/d

Phosphoglycerate kinase +2 ATP -18.8 (-37.6) 0 [3PGA] 61.2

Phosphoglycerate mutase +4.4 (+8.8) 0 [2PGA] 4.3

Enolase -3.2 (-6.4) -3.3 (-6.6) [PEP] 8.8

Pyruvate kinase +2 ATP -31.4 (-62.8) -16.7 (-33.4) [Pyr] 73.5

Net +2 ATP +2 NADH

-83.1 -102.9 ATP 1128

Class 19ObjectivesGlyco-lysis: hydrolysis of sugarGlycolysisGlycolysisSlide Number 6HexokinaseSlide Number 8PhosphohexoseisomerasePhosphofructokinase-1AldolaseSlide Number 12Aldolase intermeadiateTriose phosphate isomeraseSlide Number 15Glyceraldehyde-3-phosphate dehydrogenaseSlide Number 17Glyceraldehyde-3-phosphate dehydrogenasePhosphoglycerate kinasePhosphoglycerate kinasePhosphoglycerate mutaseSlide Number 22(bisphosphoglycerate mutase)Slide Number 24(2,3-bisphosphoglycerate)EnolasePyruvate kinaseChemical logic of glycolysisSlide Number 29Chemical logic of glycolysisEnergetics of glycolysis