1. Glycolysis
ط     Steps and key enzymes for glycolysis (irreversible reactions)
ط     Dual role of glycolysis; degrades glucose to generate ATP and source of synthesis of cell compounds
ط     Aerobic and Anaerobic glycolysis, Pyruvate and lactate as end products of glycolysis
ط     Calculation of energy and Inhibitors of glycolysis
ط     Clinical correlation
                              * Lactic acidosis
                         D

2. Introduction
fig7.4, Glycolysis occur in all cells
1. RBCs (anaerobic) – GLUT1:
NADPH (PPP), Lactate
2. Brain (aerobic) – GLUT3:
NADPH (PPP), CO2+H2O
3. Muscle (both) – GLUT4:
CO2+H2O, Lactate, Glycogen
4. AT (aerobic) – GLUT4:
NADPH (PPP), Glycogen, FA
5. Liver (both) – GLUT2:
NADPH (PPP), Glycogen, FA, Lactate, Glucose, Glucurinides
*NADPH for glutathione (organic peroxide, H2O2), FAS, Endoplasmic Reticulum, Ribose Phosphate (ATP, DNA, RNA)

3. Glycolysis fig7.6, (+8 ATP)
1. Priming Stage: (–2 ATP)
Step1:  Glu === G6P                 
Step2:  G6P  F6P       (by open chain)
Step3:   F6P === F1,6P2
                    *F6P  PFK2 (–1 ATP)  F2,6P2
2. Splitting Stage: (2 GAP)
Step4: F1,6P2  DHAP + GAP   (by splitting 3C each)
Step5:  DHAP  GAP
3. Oxidative-phosphorylation Stage: (+10 ATP)
Step6: GAP  1,3BPG
fig7.7, substrate-level phosphorylation: oxid-reduct (thiohemiacetal, Energetic) = +6 ATP
Step7: 1,3BPG  3PG   (through BPG shunt, no ATP formed in 15-25% of RBCs)
             *1,3BPG  2,3BPG M-tase  2,3BPG  2,3BPG P-tase  3PG
Step8:   3PG  2PG
Stpe9:   2PG  PEP
Step10: PEP === Pyruvate
End product:     i. Anaerobic Glycolysis; Pyruvate  LDH  2 Lactate
                                       LDH utilize NADH to form Lactate … but
                                       fig7.9, cytoplasmic NADH when Pyruvate is formed enter mitochondria:
a. GP shuttle (muscle) to generate FADH2 (mitochondrial membrane)
b. MA shuttle (liver) to generate NADH (mitosol)
                           ii. Aerobic Glycolysis; 2 Citric Acid Cycles (CO2 + H2O, complete glu oxid)
                                         *Fermentation; in yeast (Ethanol + CO2)

8. Inhibitors of Glycolysis
1. fig7.10, Deoxyglucose:  doGlucose  HK  doG6P
doG6P inhibit HK but is not a substrate (accumulate in cell)
2. fig7.11, Sulfhydryl Reagent (mercury, iodoacetate):  GAP  GAPDH (+NADH)  1,3BPG
mercury binds to –SH of GAPDH & prevents Thiohemiacetal formation, no NADH is formed
3. Fluoride (F):   2PG  Enolase  PEP
fluoride bind to Mg2+/Pi forming an ionic complex, which interferes with enolase binding
4. fig7.12, Arsenate:  GAP  GAPDH (+NADH)  1,3ABPG  PGK (+ATP)  3PG
replaces Pi when 1,3BPG is formed, therefore no ATP is yielded when 3PG is formed
Arsenic: substitutes Pi & product accumulates (no further ATP produced by glycolysis or TCA cycle)

9. Regulation of Glycolysis, Oxidation of  other monosaccharides
ط     Regulation of glycolysis (at cellular level), irreversible steps
ط     Comparison of hexokinase and glucokinase
ط     Factors affecting glycolysis
ط     Entry of fructose, galactose and mannose into glycolysis
ط     Clinical correlation:
                        * Lactose intolerance
                        * Fructose intolerance
                        * Galactosemia
                     D ,     L

11. Glucokinase (HK 4) Hexokinase (HK 1, 2, 3)
Regulation (irreversible or non-equilibrium reactions)
Glucokinase (HK 4)
fig 7.14
Hexokinase (HK 1, 2, 3)
1. In liver & pancreatic b-cells
2. high Km & low affinity for glucose (~10mM)
3. Acts only on D-Glu (diet)
4. Inducible Enzyme (Glu, F1P by release from GKRP, INS through gene expression)
5. Inhibited by F6P (by binding to GKRP)
6. Acts on Glu, in response to high Glu concentration following a meal, to remove Glu from blood.
1. In most Tissues
2. Low Km & high affinity for glucose (<0.1mM)
3. Acts on D-Glu & other hexoses (e.g. α-Glu & β-Glu)
4. Constitutive Enzyme (continuous activity)
5. Inhibited by G6P (Allosteric)
6. Acts at low Glu concentration to ensure supply of Glu to other tissues (especially Brain).  Thereby maintain concentration gradient between blood & intracellular environment
1. HK (low Km) / GK (high Km)      ….. Table              *  different kinetics!!
a) HK:   + INS (Glu-R)
   – G6P (G6P-tase)
b) GK:    + INS (gene expression)
   + F1P (GKRP)
   – F6P (GKRP)

13. a) ATP / AMP ratio (energy): 2ADP  AK  ATP + AMP;
2. PFK1: rate-limiting enzyme (F6P  PGI-ase (reversible)  G6P  Glu, Gly, PPP
a) ATP / AMP ratio (energy):
2ADP  AK  ATP + AMP;
↓ ATP  ↑↑ AMP + ↑↑ ADP by  + PFK1 (F6P  F1,6P2) / – F1,6P2-tase (F1,6P2  F6P)
b) Fig7.17  Cell Environment (cytosolic):
·  More H+ ions (low pH):
Glu (bld)  GLUT (membrane)  Glycolysis (anaerobic)  2 Lact H+ (cytosol)  symport (membrane)  2 Lact + 2 H+ (bld)
·  Balance between Lact Prod : Lact Utilize
2 Lact  LDH  Pyr  Glu, Gly, PPP
c) Tissues use other fuels (KB/FA) to preserve Glu for brain:
citrate (TCA cycle, mitosol)  don't complete TCA cycle  go to cytosol (– glycolysis)  KB/FA oxidation (mitosol)
d) Fig7.19  INS/GLG:
·  F2,6P2 promotes glycolysis & inhibit gluconeogenesis by + PFK1,
– F1,6P2-tase
*F1,6P2  F1,6P2-tase  F6P  PFK1  F1,6P2
·  fig7.25, in LIVER
§ GLG  ↑ cAMP  ↓ F2,6 P2-tase  inhibit glycolysis by – PFK1,
+ F1,6P2-tase
§ fig 7.21,  F2,6P2  F2,6P2-tase  F6P  PFK2  F2,6P2

15. fig7.24,  PFK2 a/F2,6P2-tase b  PK-A  PFK2 b/F2,6P2-tase a
cAMP inhibit glycolysis & promotes gluconeogenesis by
+ PK-A  + F2,6P2-tase,  – PFK2
§ fig7.27, INS promotes glycolysis by
i. + cAMP PDE-ase (↑ AMP) : cAMP  cAMP PDE-ase  AMP
ii. + PP-tase: PFK2 b/F2,6P2-tase a  PFK2 a/F2,6P2-tase b
iii.– PK-A: PFK2 a/F2,6P2-tase b  PFK2 b/F2,6P2-tase a
· Fig7.28, in HEART
§ Epineph acts on PK-A, which acts opposite of liver (to ↑ ATP)

17. 3. PyrK: has high Km as GK (need high substrate concentration in diet / INS)
a) fig7.30, PyrK a  PK-A  PyrK b  PP-tase  PyrK a
b) cAMP (GLG) promotes + PK-A:  PyrK a "active" è PyrK b "inactive"
c) F1,6P2 (PFK1) promotes + PP-tase: PyrK b "inactive" è PyrK a "active"
d) PyrK is inhibited (–) by ATP, alanine
* GLG inhibit PyrK by promoting gluconeogenesis

19. Clinical Correlation
1. fig7.17,  Lactic Acidosis cc7.5
a. increase in Lact Prod: Excessive exercise, convulsions, Angina, Pulmonary Failure
 ↓bld circulation  ↓O2 to cell  ↑Lact + H+ in bld
b. decrease in Lact Utilize: Liver diseases, ethanol, Phenformin (drug)
 ↓gluconeogenesis + ↓TCA cycle + ↓O2 to cell è ↑Lact + H+ in bld
2. fig, Fructose Intolerance cc7.3
Fru  FK  F1P  F1Paldolase  DHAP + GAP
a. deficiency in F1Paldolase lead to F1P accumulate  deplete of Pi & ATP 
Osmotic lysis
b. deficiency in FK is less important (Fru  F6P or Sucrose)
3. fig, Galactosemia  cc8.3
Gal  GalK  Gal1P  Gal1PUT-ase  UDP-Gal  UDP-Glu  Galctitol
a. deficiency in GalK inhibit Gal to Glu drived from Lactose (cataract, CNS damage)
b. deficiency in Gal1PUT-ase accumulates Gal1P (liver damage)

20. Clinical Correlation
2. fig, Fructose Intolerance cc7.3
Fru  FK  F1P  F1Paldolase  DHAP + GAP
a. deficiency in F1Paldolase lead to F1P accumulate  deplete of Pi & ATP 
Osmotic lysis
b. deficiency in FK is less important (Fru  F6P or Sucrose)

21. Clinical Correlation
3. fig, Galactosemia  cc8.3
Gal  GalK  Gal1P  Gal1PUT-ase  UDP-Gal  UDP-Glu  Galctitol
a. deficiency in GalK inhibit Gal to Glu drived from Lactose (cataract, CNS damage)
b. deficiency in Gal1PUT-ase accumulates Gal1P (liver damage)