hexokinase

lactate dehydrogenase

fermentation oxidizes NADH —> NAD+, reduces pyruvate to lactate

fructose 1,6 bisphosphatase

gluconeogenesis

epinephrine

cAMP —> glycogen breakdown

glutathione

reduces reactive oxygen species. dependent on NADPH from PPP G6PD, glutathione reductase

G6PD

glucose 6 phosphate dehydrogenase - first rate limiting enzyme of the pentose phosphate pathway. oxidizes G6P —> 6-phosphogluconolactone, produces NADPH

pentose phosphate pathway (PPP)

anabolic process produces NADPH for anabolic process, ribose for nucleotide synthesis. used by both eukaryotes and prokaryotes in the cytoplasm

insulin

anabolic - requires NADPH to store glucose

parathyroid hormone

raises blood calcium. promotes bone resorption by osteoclasts and inhibits osteoblasts

calcitonin

lowers ca levels. promotes bone formation by osteoblasts and inhibits bone resorption by osteoclasts

glucagon

catabolic - inhibits G6PD/PPP

glucokinase

liver hexokinase with a lower affinity for glucose. converts to glucose 6 phosphate irreversible

phosphofructokinase

glycolysis irreversible, rate limiting adds phosphate fructose 6 phosphate → fructose 1,6-bisphosphate

hexokinase

irreversible removes glucose from concentration by converting into glucose 6 phosphate

PEPCK

phosphoenolpyruvate carboxykinase bypasses irreversible phosphoenolpyruvate to pyruvate. reversible converts oxaloacetate to phosphoenolpyruvate for gluconeogenesis

GAPDH

glyceraldehyde-3-phosphate dehydrogenase. reversible reaction in both glycolysis and gluconeogenesis (glyceraldehyde 3 phosphate → 2,3 bisphosphoglycerate)

GLUT2

low affinity (high Km) transporter in hepatocytes and pancreatic cells. for excess glucose to storage

GLUT4

normal affinity (lower Km than GLUT2) glucose transporter in adipose and muscle. activity increased by insulin

malate dehydrogenase

TCA

a-ketoglutarate

TCA

irreversible glycolysis

hexokinase, pfk-1, pyruvate kinase.

reversible

phosphohexose isomerase, aldolase, triose phosphate isomerase, g3p dehdyrogenase, phosphoglycerate kinase, mutase, enolase

irreversible gluconeogenesis

pyruvate carboxylase, glucose 6 phosphatase, fructose 1,6 bisphosphatase, phosphoenolpyruvate carboxykinase

opposite of hexokinase

glucose 6 phosphatase

opposite of phosphofructokinase-1

fructose 1,6 bisphosphatase

opposite of pyruvate kinase

PEPCK and pyruvate carboxylase

opposite of glucose 6 phosphatase

hexokinase

opposite of fructose 1,6 bisphosphatase

pfk-1

opposite of PEPCK

pyruvate kinase

rate limiting glycogen synthesis

glycogen synthase

rate limiting PPP

glucose 6 phosphate dehydrogenase

rate limiting glycolysis

PFK 1

rate limiting gluconeogenesis

1,6 bisphosphatase

rate limiting TCA

isocitrate dehydrogenase

rate limiting glycogenolysis

glycogen phosphorylase

rate limiting ketogenesis

HmG-CoA synthase

rate limiting cholesterol synthesis

HmG-CoA reductase

pyruvate carboxylase

irreversible gluconeogenesis converts pyruvate to oxaloacetate

pyruvate dehydrogenase cofactors

E1: pyruvate dehydrogenase E2: dihydrolipoyl transacetylase E3: dihydrolipoyl dehydrogenase. requires thiamine (TPP), lipoic acid, coenzyme A (CoA), flavin adenine dinucleotide (FAD), nicotinamide adenine dinucleotide (NAD+) and mg cofactors

pyruvate dehydrogenase E1

pyruvate dehydrogenase

pyruvate dehydrogenase E2

dihydrolipoyl transacetylase

pyruvate dehydrogenase E3

dihydrolipoyl dehydrogenase

pyruvate oxidation steps

1. pyruvate binds E1 (pyruvate dehydrogenase). TPP grabs pyruvate and forms hydroxyethyl

2. E2 swinging arm transfers intermediates. E2 forms acetyl CoA

3. E3 reoxides E2 arm, reduces fad → fadh2

4. nad+ → nadh regenerates fad

fatty acid synthase

palmitate synthase forms 16:0 palmitate from acetyl coA and malonyl coA

acetyl coa carboxylase

adds CO2 to acetyl COA —> malonyl coA or fatty acid synthesis requires biotin and atp

rate limiting fatty acid synthesis

acetyl coa carboxylase malonyl coa formation

fatty acid synthesis

malonyl coa → malonyl acp attachment, carbonyl reduction, dehydration, reduction of double bond

rate limiting beta oxidation

carnitine acyltransferase

enoyl coa isomerase

rearranges cis bonds to trans to isolate double bonds for beta oxidation

2,4 dienoyl coa reductase

converts two conjugated bond into one double bond in between

LCAT

lecithin-cholesterol acyltransferase attaches fatty acid to cholesterol forms cholesteryl ester. activated by hdl/apoA-1

cholesteryl ester transfer protein

LDL synthesis attaches HDL cholesteryl ester to IDL

apoA-1

HDL ligand activates LCAT for cholesterol esterification

apoB-48

chylomicron secretion

apoB-100

LDL liver uptake

apoL-II

binds lipoprotein lipase (LPL) in blood stream

apoE

chylomicron remnants and VLDL liver uptake

rate limiting ketolysis

succinyl coa acetoacetyl coa transferase acetoacetate → acetoacetyl coA uses succinyl coa from tca, not located in liver

ketogenesis

acetyl coa → acetoacetyl CoA → HMG CoA → Acetoacetate ketone body → reduced into 3-hydroxybutyl ketone body + acetone fruity breath

ketolysis

3-hydroxybutyl → acetoacetate → acetoacetyl coA → 2 acetyl coA

protein catabolism

primarily releases amino acids. glucogenic and ketogenic deamination → glucose and ketone bodies. NH3 production removed via urea cycle

pyruvate carboxylase

converts pyruvate to oxaloacetate