OXIDATION OF HEXOSES

From Marks' and Harper's

Glucose Transporters (GLUT) Mnemonic

BBB - GLUT I - Blood (erythrocytes), Baby (fetus), Blood Brain Barrier

Kids LiPs - GLUT II - Kidney, Liver, Pancreas,
are

PiNK - GLUT III - Pancreas, Neurons, Kidney

Mother - GLUT IV - Muscle (myocytes), Fats (adipocytes)
Father

3 Conditions for anaerobic glycolysis

1. Limited O₂ supply

2. Few or no mitochondria in cell

3. Greatly increased ATP demands

Lactate dehydrogenase role in anaerobic glycolysis

Oxidizes NADH from glycolysis by reducing pyruvate to lactate

Rate limiting enzyme of glycolysis

Phosphofructokinase-1 (PFK-1)

Allosteric inhibitor and activator of PFK-1

Inhibitor - ATP
Activator - AMP

Inherited disorders of fructose metabolism (2 of em)

Essential fructosuria - fructokinase deficiency

Hereditary fructose intolerance - deficiency of F1P cleavage by aldolase B

2 phases of glycolysis and what they generate

1. Preparative phase
   Generates F-1,6-bis-P

2. ATP-generating phase
   4 ATP, 2 NADH, 2 pyruvate

Enzyme that cleaves F-1,6-bis-P into two triose phosphates

Aldolase

Two triose phosphates formed by cleavage of Fructose 1,6-bisphosphate

Glyceraldehyde 3-phosphate (G3P)
Dihydroxyacetone phosphate (DHAP)

Isomerizes DHAP to G3P

Triose phosphate isomerase

Oxidizes aldehyde group of G3P to an enzyme-bound carboxyl group, and transfers the electron to NAD⁺ to form NADH

Glyceraldehyde 3-P dehydrogenase

Enzyme that catalyzes transfer of high-energy phosphate from 1,3-bisphosphoglycerate to ADP, forming ATP and producing 3-Phosphoglycerate

Phosphoglycerate kinase

Converts 3-phosphoglycerate to 2-phosphoglycerate, generating a high-energy phosphate bond

Phosphoglycero-mutase

Removes water from 2-phosphoglyerate to form Phosphoenolpyruvate (PEP)

Enolase

Transfers phosphate from PEP to ADP, forming ATP and producing pyruvate

Pyruvate kinase

The rate-limiting enzyme of fructose metabolism

Aldolase B

Enzyme that helps produce Glucose-1-P from Galactose-1-P and UDP-glucose

Galactose-1-P Uridylyltransferase

pKa of lactic acid

3.85

Regulator of glucokinase in the liver, its action, and when it acts

Glucokinase Regulator Protein
Binds to glucokinase when glucose levels in the hepatocyte are low, complex translocates to the nucleus
When glucose levels rise, complex re-enters cytoplasm, glucokinase is released from GKRP

3 PFK-1 isoenzymes

M - muscle
L - liver
C - common

PFK-1 isoenzyme in Erythrocytes

M and L

Where PFK-1 C isoenzyme is found in highest conc.

Platelets, placenta, kidney, fibroblasts

AMP and ATP regulation most affects which PFK-1 isoenzyme

M and L

Pyruvate kinase does not regulate glycolysis in which tissues

Brain, Heart, Muscle
M1 pyruvate kinase isoenzyme that contains no allosteric sites