Integration of MetabolismIntegration of Metabolism

FUELS, METABOLITES AND DISORDERS

FUELS URINE BILE/FECES METABOLITES

METABOLITES

Starch, Glucose NH4,+ SO42-, HPO4

2- Cholesterol,Mannose Creatinine Bile Acids Sucrose (Fructose) Urea, Urate Bilirubin Amino Acids 17-Ketosteroids, -alanine StercobilinGlycerol -Aminoisobutyrate Lipid Fat, Phospholipid (Steatorrhea)Fatty Acids Ketone BodiesSorbitol PolyaminesNucleic Acids(minor) Xanthurenic acidLactose(Galactose) Urobilinogen, UrobilinKetone Bodies

FUELS, METABOLITES AND DISORDERS

FUELS URINE BILE/FECES METABOLITES

METABOLITES

Starch, Glucose NH4,+ SO42-, HPO4

2- Cholesterol,Mannose Creatinine Bile Acids Sucrose (Fructose) Urea, Urate Bilirubin Amino Acids 17-Ketosteroids, -alanine StercobilinGlycerol -Aminoisobutyrate Lipid Fat, Phospholipid (Steatorrhea)Fatty Acids Ketone BodiesSorbitol PolyaminesNucleic Acids(minor) Xanthurenic acidLactose(Galactose) Urobilinogen, UrobilinKetone Bodies

1-3

Metabolic Diseases and Metabolites Biotin deficiency: propionic acid, branched -ketoacids

Amino Acids -->--> Propionic Acid ----> Succinyl CoA

B12 deficiency: methylmalonate, homocysteine Hemolytic anemia and certain porphyrias: bilirubin PKU: Phe, phenyllactate, phenylacetate, phenylpyruvate Hypoxia: lactic acid

Hyperammonemia: citrulline, argininosuccinate, etc.

Biopterin or biopterin reductase deficiency: decrease in 5-hydroxy-indoleacetic, vanillyl mandelic acid, homovanillic acids

1-3

Metabolic Diseases and Metabolites (continued) Folic acid deficiency: formiminoglutamic acid (FIGLU) Diabetes mellitus: glucose (blood and urine), HbA1c, DKA

Fructose intolerance: fructose or fructose 1-Pi *Cystinuria with basic A.A. renal transporter defect: cystine

*Hartnup's disease: neutral aminoaciduria (Trp loss -> Niacin ) Homocystinuria: homocysteine

Gaucher's disease: glucocerebrosides (lysosomal disorder)

Metabolic Disturbances and Fuel Intolerances

Carbohydrate Intolerance Protein Intolerance

Diabetes mellitus Methylmalonyl aciduria Fructose Intolerance Maple Syrup urine disease Cushing's Disease (ACTH) Vitamin B12/Biotin deficiency Galactosemia Urea cycle deficiency Lactose Intolerance Phenylketonuria

Lipid Intolerance

LPL Def. (VLDL or Chylo ) MCAD

1-3

Exercise Intolerance: Ketoacidosis/Ketonemia(Early vs. Prolonged)

Decreased PFK-1 Diabetic ketoacidosisMcArdles' disease Organic acidurias Carnitine, CAT1 deficiency Alcoholic ketoacidosisMCAD deficiency Glycogen storage disease

1- 4

Glycogen Storage:

Glucose 6-phosphatase (Type 1) - Von Gierke’smild to severe hypoglycemia - only GNG tissues affected

Lysosomal -glucosidase (Type 2) - Pompe’sno hypoglycemia --> fatal - all tissues affected

Amylo-1,6-glucosidase (Type 3) - Cori’smild hypoglycemia

Glycogen Phosphorylase - McArdle’sno hypoglycemia - low lactate upon exercise

Glycogen Synthase - hypoglycemia / hyperketonemia

Screening and Treatment of Metabolic Disease

Disease Screening Programs Methods of Treatment

Sickle Cell Disease * Dietary and Vitamin Therapy Tyrosinemia I Drug, hormone or metabolitePhenylketonuria * administration (allopurinol,Galactosemia * benzoic or phenylacetic acid, Homocystinuria insulin, carnitine, heme, etc.)Biotinidase Deficiency Enzyme replacement Maple syrup urine disease Genetic engineering (stem cell Adrenal hyperplasia replacement)Hypothyroidism (Cretinism) * Organ transplantation

1-4

Allosteric Regulation Glycolysis: Hexokinase, Phosphofructokinase-1, Pyruvate kinase (ATP, Ala) Gluconeogenesis: Pyruvate carboxylase, Fructose 1,6-bisphosphatase Glycogenolysis: Glycogen phosphorylase kinase ( Ca2+ ) Glycogen phosphorylase

(AMP, ATP, Glucose) Glycogenesis: Glycogen Synthase (Glucose 6-P) Fatty acid Synth: Acetyl CoA carboxylase Beta Oxidation : CAT I (Malonyl CoA), Thiolase (Acetyl CoA)

-hydroxy fatty acyl CoA dehyd. (NADH) Cholesterol Synth: HMGCoA reductase (Cholesterol) Pyrimidine Synth: Carbamyl Pi Synthetase II (UTP) Purine Synthesis : PRPP amidotransferase (Nucleotides) Heme Synthesis: -Aminolevulinic acid synthase (Heme) Ammoniagenesis: Glutamate Dehydrogenase (ADP/GDP) Citric Acid Cycle Citrate Synthase, IC and KG Dehyd.

(NADH, ATP) Urea Cycle Carbamyl Pi Synthetase I (N-Acetyl Glu)

Covalent Modification (Response of Activity to Phosphorylation, (Acute or Fine Control)

Glycogen phosphorylase () Adipose triacylglycerol lipase () Glycogen synthase () Acetyl CoA carboxylase () Hepatic pyruvate kinase () HMG CoA reductase () Pyruvate dehydrogenase () Phosphorylase b kinase ()

1-4

Compartmentation

Cytosolic: Glycolysis, pentose pathway, fatty acid / triacylglycerol synthesis, nucleotide synthesis, cholesterol biosynthesis

Mitochondrial: TCA, electron transport, oxidation of fatty acids, ketone body formation, pyruvate dehyd. Interplay: Urea synthesis; gluconeogenesis; fatty acid synthesis, steroid biosynthesis and heme biosynthesis

Shuttles: Malate/aspartate, DHAP/glycerol phosphate (electrons) , citrate (acetyl CoA) , carnitine (F.A.s)

Compartmentation

Cytosolic: Glycolysis, pentose pathway, fatty acid / triacylglycerol synthesis, nucleotide synthesis, cholesterol biosynthesis

Mitochondrial: TCA, electron transport, oxidation of fatty acids, ketone body formation, pyruvate dehyd. Interplay: Urea synthesis; gluconeogenesis; fatty acid synthesis, steroid biosynthesis and heme biosynthesis

Shuttles: Malate/aspartate, DHAP/glycerol phosphate (electrons) , citrate (acetyl CoA) , carnitine (F.A.s)

1-51-5

A

A - Glycogen Storage Disease - Type I

B

B - Glucose 6-Pi Dehydrogenase

Deficiency

C

C - McArdles’ or Cori’s Disease

D

D - Galactosemia

1-5

UDP-Glucouronate

BilirubinDiglucuronide

E - Crigler-Najjar Syndrome (bilirubin glucuronyltransferase)

E

Glucose 6-PiGlucose 6-Pi

A - Glycogen Storage Disease (Type I):

Both GNG and Glycogenolysis HallMarks:

Excess Glycogen AccumulationHypertriglyceridemiaFasting HypoglycemiaHyperuricemia

B - Glucose 6-Pi Dehyd. Def. - Acute Hemolytic Anemia:

Stress --> Red Cell [NADPH] H2O2 and Lipid Peroxides MetHb Hemolysis Hematocrit Haptoglobulin Bilrubin/BDG

1-5/6

Glycogen

Glucose 6-Phosphate Feed-Fast Cycles

DHAP +Acetyl CoA

VLDL

Lactate

RBC

Adipose

Fatty Acids + Glycerol

Blood Glucose

PRPP

Purines

Glycogen StorageDisease Type I

A - Homocystinuria, B6 responsive

Cytosolic NADH Utilization: Mitochondrial and Citrate Shuttles Pyruvate --> Lactate Glycerol 3-Pi Synthesis for TAG A.A. Metab.: Ser -->--> 3-Phosphoglycerate

1-6

APyruvate

OAA

Asp

Homocysteine

DHAPDHAPDHAP

B - Diabetes (IDDM, Type I) Lipolysis > ketone body utilization

A - StarvationC - Carnitine/CAT I Def. Hypoketonemia

- 1-7Acetyl CoAB

-

Ketoacidosis (DKA)

+

C

Acetyl CoAAcetyl CoA

A - Hyperuricemia/Gout ( HGPRT ) (Lesch-Nyhan Syndrome)

A

B - Hypoxia or Phosphate Trapping O2 Oxid. Phosp. & ATP ) Pi Oxid. Phosp., Glycolysis, Glycogenolysis

B

C - Hyperuricemia - urate underexcretion (renal failure, lactic acidosis, alcoholism)

C

PRPP 1-8

PRPPPRPP

A’

A

A - Orotate Phosphoribosyl transferase A’ - OMP Decarboxylase

Treatment: feed uridine or cytidine

Phosphate Trapping: Fructose Intolerance, Galactosemia, Von Gierke’s Glycogen Storage

Orotic Aciduria - Poor growth, megaloblastic anemia - unresponsive to folate / B12

1-8

UMPSynthase

PRPPPRPPOROTATE

1-9

TheBiotinCycle

TheBiotinCycle

Dietary BiotinDietary Biotin

• Only Four Enzymes in Humans Require Biotin:

Pyruvate Carboxylase (mito.)Propionyl CoA Carboxylase “Acetyl CoA Carboxylase (cyto.)Methyl crotonyl CoA Carboxylase (Leu catabolism)

• Many other carboxylases don’t require biotin:

Malic enzyme, PEPCK, Carbamoyl Pi Synthetases, etc.

• Biotin/Biotin-like Deficiency:

Biotinidase Deficiency Holocarboxylase Deficiency Raw egg ingestion (avidin)

1-9

Oral biotinsupplementoften effective

Multiple Carboxylase Deficiency (Organoaciduria)

Ketoacidosis - ketoacid of amino acids , anion gap Hypoglycemia and Lactic acidosis - pyruvate carboxylase Dermatitus - fatty acids synthesis - acetyl CoA carboxylase Hyperglycinemia - glycine cleavage enzyme and glycine Hyperammonemia but pH low - N-acetyl Glu synthase , urea cycle

Methylmalonyl aciduria: enzyme or B12 deficiency ,

homocysteine may also rise

1-10

Summary of Multiple Carboxylase Deficiency

Mitochondrial propionic acid, branched chain ketoacids and their CoA derivatives

Secondary Carnitine deficiency, -oxidation

Energy

Glycine Cleavage Enzyme

N-acetyl Glu Synthase

Gly

N-Acetyl Glu

Mito. CoA Depletion or inhibition

Other Organoacidurias: Maple syrup urine, methylmalonic aciduria and HMGCoA lyase defect act similarly

NH3

Atypical PKU - Biopterin Reductase Deficiency

PhenylacetatePhenyllactatePhenylpyruvate

5 HO-indoleacetic acid

Features: Mental retardation despitePhe restriction ; give tetrahydrobiopterin (won’t cross blood brain barrier) - giveL-DOPA and 5-HO-Trp

Melatonin

1-11

B - Albinism

Parkinson Disease

Other PKUs:

Classical : (> 95 % of PKU’s) Most common inborn error - only degradative pathway involved - restrict Phe to avoid post-natal mental retardation

Maternal : Mother is -/+ or -/- for PKU - avoid aspartame (aspartylphenylalanine methyl ester)

Serotonin: (CNS) - Neurotransmitter; (Platelet) - vasoconstrictor; (GI) - enterochromaffin cells (tumors)

Pheochromocytoma: Cancer of the adrenal medulla. Overproduction of epinephrine - vanillylmandelic high in urine - hypertension

A - Heriditary Fructose Intolerance (HFI)

B - GNG Deficiency: Lactic Acidosis / Hypoglycemia

C - Galactosemia

GLYCOLYSIS 1

A

B

B

C

1-12

Pentoses

*

A

A - Hemolytic Anemia - PK deficiency(C.C. 7.8)

1-13GLYCOLYSIS 2

PKA, ATP

Pyruvate Dehydrogenase

Five Coenzymes: NAD+, Thiamin, Pantothenic acid, lipoic acid, FAD

Five Enzymes: PDH (E1), Lipoyl dehyd. (E2), and transacetylase (E3)

kinase and phosphatase

1-14E3 Deficiency:lactic acid, KG and -ketoacids(bcaa)

Feasting - Hepatic- High Glucose

Muscle Uptake, Growth

1-15

Fasting - Hepatic -Low Glucose

KetoneBodies

Ala,PKA

GNG Energyfrom -oxidation

Urea

Mevinolin, Lipotor - “statins”- lower plasma cholesterol 20-60 %

A

A - Smith-Lemli-Opitz (SLO) syndrome - 7-DHC reductase deficiency - birth defects

1-18

[C30]

[C30]

METABOLISM INCREASE DECREASE

Amino acid degradation Starvation Growth and develop.High Protein Diet InsulinGlucocorticoidsGlucagon

Glycolysis Insulin GlucagonGluconeogenesis Glucagon

Glucocorticoids InsulinPentose Pathway Insulin Starvation

CarbohydrateFeeding

Lipogenesis Low fat dietHigh Carbohydrate Starvation

Lipolysis Glucagon InsulinCholesterol Biosynthesis Insulin, Glucagon

Loss of Bile acids, Starvation, Dietary Cholest. Dietary Cholest.

Glycogenesis Insulin GlucagonGlyogenolysis Glucagon Insulin

Epinephrine

Metabolic Entry Points of Amino Acids

Pyruvate: Trp, Thr, Gly, Ala, Cys, Ser

Acetyl CoA/Acetoacetyl CoA (no net carbohyd.synthesis):

Ile, Trp, Phe, Leu, Tyr, Lys

-Ketoglutarate: Glu, Gln, His, Pro, Arg, Orn

Succinyl CoA: Met, Thr, Val, Ile

Oxaloacetic Acid: Asp, Asn

Fumarate: Asp (urea cycle), Phe, Tyr