In chapter 11, you will learn to: Know the overall equation for glycolysis, know the names of the intermediates of glycolysis from glucose to pyruvate, know the name of the enzymes involved in each step, know the co-factors involved in each step of glycolysis, be able to recognize the structures of each intermediate of glycoysis,. | Chapter 11 (Part 1) Glycolysis Glycolysis Anaeorbic process Converts hexose to two pyruvates Generates 2 ATP and 2 NADH For certain cells in the brain and eye, glycolysis is the only ATP generating pathway Glucose+2ADP+2NAD++2Pi -> 2pyruvate+2ATP+2NADH+2H++2H20 Glycolysis Essentially all cells carry out glycolysis Ten reactions - same in all cells - but rates differ Two phases: First phase converts glucose to two G-3-P Second phase produces two pyruvates Products are pyruvate, ATP and NADH Three possible fates for pyruvate Phase I: Cleavage of 1 hexose to 2 triose Phase II: Generation of 2 ATPs, 2 NADH and 2 Pyruvates Hexose Kinase 1st step in glycolysis; G large, negative This is a priming reaction - ATP is consumed here in order to get more later ATP makes the phosphorylation of glucose spontaneous Hexokinase also functions in other processes Glucose import Directing glucose to other pathways Not 1st committed step in glycolysis Different Hexokinase Isozymes Two major forms . | Chapter 11 (Part 1) Glycolysis Glycolysis Anaeorbic process Converts hexose to two pyruvates Generates 2 ATP and 2 NADH For certain cells in the brain and eye, glycolysis is the only ATP generating pathway Glucose+2ADP+2NAD++2Pi -> 2pyruvate+2ATP+2NADH+2H++2H20 Glycolysis Essentially all cells carry out glycolysis Ten reactions - same in all cells - but rates differ Two phases: First phase converts glucose to two G-3-P Second phase produces two pyruvates Products are pyruvate, ATP and NADH Three possible fates for pyruvate Phase I: Cleavage of 1 hexose to 2 triose Phase II: Generation of 2 ATPs, 2 NADH and 2 Pyruvates Hexose Kinase 1st step in glycolysis; G large, negative This is a priming reaction - ATP is consumed here in order to get more later ATP makes the phosphorylation of glucose spontaneous Hexokinase also functions in other processes Glucose import Directing glucose to other pathways Not 1st committed step in glycolysis Different Hexokinase Isozymes Two major forms hexokinase (all cells) & glucokinase (liver) Km for hexokinase is 10-6 to 10-4 M; cell has 4 X 10-3 M glucose Km for glucokinase is 10-2 M only turns on when cell is rich in glucose Glucokinase functions when glucose levels are high to sequester glucose in the liver. Hexokinase is regulated - allosterically inhibited by (product) glucose-6-P Rx 2: Phosphoglucoisomerase Uses open chain structure as substrate Near-equilibrium rxn (reversible) Enzyme is highly stereospecific (doesn’t work with epimers of glucose-6-phosphate Rx 2: Phosphoglucoisomerase Why does this reaction occur?? next step (phosphorylation at C-1) would be tough for hemiacetal -OH, but easy for primary -OH isomerization activates C-3 for cleavage in aldolase reaction Rx 3: Phosphofructokinase PFK is the committed step in glycolysis! The second priming reaction of glycolysis Committed step and large, -DG – means PFK is highly regulated b-D-fructose-6-phosphate is substrate for rxn Phosphofructokinase is highly regulated ATP .
