Biochem-Amino Acid Metabolism

Front 1

How are Amino Acids utilized in different nutritional states?

Back 1

Fed State:
AA carbon --> glucose --> glycogen (energy storage)
AA carbon (excess AAs) --> acetyl CoA (fatty acid) --> triglycerides (adipose tissue) energy storage

Fasting State: AA carbon
-CO2
-pyruvate
-TCA cycle intermediates
-acetyl CoA, acetoacetate
(all for energy production)

Front 2

Why are amino acids glucogenic, ketogenic or both?

Back 2

Glucogenic - AA can be converted into glucose
Ketogenic - AA can be converted into ketone bodies
Glucogenic & Ketogenic - AA can be converted into both glucose and ketone bodies

Front 3

What are the glucogenic AA's?

Back 3

-Alanine
-Arginine
-Asparagine
-Aspartate
-Cycteine
-Glutamate
-Glutamine
-Glycine
-Proline
-Serine
-histidine
-methionine
-valine

Front 4

What are the ketogenic AA's?

Back 4

-leucine
-lysine

(The ones that start with "L")

Front 5

What are the AA's that are both glucogenic and ketogenic?

Back 5

-tyrosine
-threonine
-isolucine
-phenylalanine
-tryptophan

(ones that start with "T" plus 2--isolucine & phenylalanine)

Front 6

What are the essential AA's?

Back 6

-pretty much all the glucogenic ones except for histidine, methionine, and valine
-tyrosine

Front 7

What are the main pathways for the synthesis of nonessential AA's?

Back 7

-AA's synthesized from glycolysis intermediates
-tyrosine
-AA's synthesized from alpha-ketoglutarate
-AA's synthesized from oxaloacetate

Front 8

What are the characteristic enzyme deficiencies in diseases of AA metabolism?

Back 8

-Pyridoxal-phosphate ---> transamination & deamination
-tetrahydrofolate ---> metabolism of serine glycine, methionine and histidine
-B12 Vitamin ---> methionine metabolism
-Thiamine-pyrophosphate (B1) and lipoate ---> oxidative decarboxylation of branched chain AA's

(those 4 are derived from vitamins)

tetrahydrobiopterin ---> hydroxylation of phenylalanine, tyrosine, and tryptophan

Front 9

What are the metabolites that have abnormal levels in diseases of AA metabolism?

Back 9

look at disease chart on last slide of lecture

Front 10

What is Homocystinuria?

Back 10

cystathione synthase, or vitamin B6, B12, or folic acid deficiency
AA metabolism: Methionine
Accum. metaboilites: homocysteine, methionine
Symptoms: myocardial infarction, mental retardation, ectopia lentis

Front 11

What is the maple syrup urine disease?

Back 11

a-keto acid dehydrogenase deficiency
AA metabolism: Leu, Ile, Val (I Love Vermont maple syrup)
Accum. metabolites: Leu, Ile, Val and their a-ketoacids
Symptoms: maple syrup odor of urine, neurological problems
treatment: diet restricted in branched chain AA (BCAA)

Front 12

What is Phenylketonuria?

Back 12

phenylalanine hydroxylase or tetrahydrobiopterine deficiency
AA metabolism: Phe
Accum. metabolites: Phe, phenyllactate, phenylacetate, phenylpyruvate
Symptoms: musty odor of urine, neurological problems, hypopigmentation
treatment: Phe-restricted, Tyr supplemented diet, avoid aspartame

Front 13

What is Albinism?

Back 13

tyrosinase is deficient
AA metabolism: Tyr
Accum. metabolites: none
Symptoms: white skin, hair, pink eyes

Front 14

What is Tyrosinemia 1?

Back 14

fumaryl acetoacetate hydrolase deficiency
AA metabolism: Tyr
Accum. metabolites: succinylacetone, fumarylacetoacetate
Symptoms: liver failure, kidney failure
treatment: dietary restriction of phenylalanine and tyrosine

Front 15

What is Alkaptonuria?

Back 15

homogentisate oxidase deficiency
AA metabolism: Tyr
Accum. metabolites: homogentisic acid accumulates in urine
Symptoms: urine turns dark, black pigmentation in eye, ear arthritis

Front 16

What are the major end products of amino acid degradation?

Back 16

-pyruvate
-TCA cycle intermediates
(oxaloacetate, fumarate, succinyl CoA, a-ketoglutarate)
-acetyl-coa, acetoacetate

Front 17

Asparaginase is used as what?

Back 17

antileukemic drug
-asparagine is required for growth of fast dividing leukemic cells

(AA's that are degraded to oxaloacetate)

Front 18

histidinemia

Back 18

-disease due to a deficiency in histidase
-elevated levels of histidine in blood and urine

Front 19

folic acid deficiency

Back 19

-excrete increased amounts of FlGlu in urine
-FlGlu excretion used to monitor folic acid deficiency

Front 20

Pellagra

Back 20

lack of tryptophan and niacin (vit B3) in diet
-4 D's: Dermatitis, Diarrhea, Dementia, and if untreated Death!