Exam 2.1

Carbon skeletons of glycogenic AA degrade to what?

Pyruvate OR 4-C or 5C intermediates of TCA cycle

Cyteine is used to produce taurine. Why is taurine important?

Retina, functions as bile salt, and inhibitory neurotransmitter

What is a principal methyl donor?

SAM (s-adenosyl methionine)

Which 4 AA can be converted to pyruvate?

Serine, Glycine, Cysteine, and Alanine

Define deamidation

The amino group that is cleaved is the second amino group on the amino acid. It is cleaved but not transferred.

Define transamidation

The amino group that is cleaved is the second amino group on the amino acid. It is transferred to a carbon skeleton or to an amino acid

Alanine is converted to what?

pyruvate

What does degradation of cysteine yield?

pyruvate and sulfite

What is cysteine used for?

protein and glutathione synthesis

Uricotelic organisms release nitrogen as?

the purine, uric acid

Citraline and Aspartate are converted to arginosuccinate by what enzyme? Does this reaction require energy?

Argininosuccinate synthetase . The reaction requires ATP.

What enzyme catalyzes the transamidation reaction of aspartate to asparagine?

Asparagine Synthetase

Which AA breakdown to the TCA cycle intermediate, OAA?

Asparagine and Aspartate

What is OAA transaminate to?

Aspartate

Which 2 AA form OAA

Aspartate and Asparagine

BCAA metabolism requires what?

B12, thiamin (TPP), Niacin (NADH), Mg2+ and Biotin (B7)

In high concentrations, what gives urine it odor?

BCAA

What does the ending "ingen" mean?

"Ingen" is inactive until it is cut, then it will be an active for. Ex. Pepsinogen into Pepsin

What becomes of the C Skelton (alpha kept acid) after AA catabolism?

Fatty acids, glucose and/or ketone bodies, AND energy + CO2

Arginosuccinate is converted to arginine and fumarate by what enzyme?

Argininosuccinate lyase or argininosuccinase

What symptoms occur when a lack of vitamin B6 decreases the formation of PLP?

A decrease in synthesis of heme, neurotransmitters, and NAD, resulting in pellagra like symptoms and anemia

Explain the 6 steps of nitrogen within the digestive tract

1. Gastrin is released from stomach into bloodstream → results in release of gastric juices 2. HCL converts pepsinogen to pepsin (low pH) → begins to digest proteins 3. Partially digested proteins enter duodenum → CCK and Secretin released → CCK also stimulates nearby mucosal cells to release enteropeptidase (protease) and cleaves trypsinogen to produce trypsin. 4. Pancreas stimulated and it releases pro-enzymes and bicarbonate → bicarbonate neutralizes chyme 5. Proenzymes converted to enzymes → digest polypeptides to form amino acids. 6. Intestinal enzymes within mucosal cells complete digestion

What 3 mechanisms are needed to bring an amino acid into an enterocyte?

1. PEP 1: dipeptide and hydrogen enter into cell through PEP1 2. Na+/H+: too much hydrogen brought in through PEP1 so Na+/H+ to get rid of H+ 3. Na+/K+: too much Na+ brought into cell through Na+/H+ so Na+/K+ to get rid of Na+

What are the 5 metabolic disorders of the urea cycle?

1. hyperammonemia type I. 2. hyperammonemia type II. 3. citrullinemia. 4. argininosuccinicaciduria. 5. hyperargininemia.

For every 2 C acetyl residues entering TCA cycle, how many C leave as CO2?

2 Carbons

Carbon skeletons of ketogenic AA degrade to what?

Acetyl Coa or Acetotacetate

Which for 8 AA can for acetyl CoA or acetoacetate?

Acetyl-CoA: Lysine, Iloleucine, Threonine, and Tryptophan Acteoacetate: Pheylanine and tyrosine Both: LEUCINE

Which AA are glycogenic (13)?

Alanine, Arginine, Asparagine, Aspartate, Cysteine, Glutamate, Glutamine, Glycine, Histidine, Methionine, Proline, Serine, Valine. (AAAA C GGG HMP SV)

An amino acid is catabolized into two parts. What are they?

Amino nitrogen & C Skelton

What two substrates are needed to start the urea cycle?

Ammonia, CO2 and H2O

Define Marasmus disease

An individual with Marasmus disease is not only not getting the amino acids and nutrients that they need, they are also not getting enough calories in their diet at all.

What enzyme is deficient in Hyperammonemia Type I?

CPS-1 (carbamoyl phosphate synthetase)

How is argininosuccinicaciduria treated?

Can be treated by arginine supplements

What enzyme converts NH4 and CHO3 to Carbonyl phosphate? Does this reaction require energy?

Carbamoylphosphate synthetase (CPS-1). 2 ATP.

What groups of people may experience a positive nitrogen balance?

Children, pregnant women, and individuals recovering from major illness are likely to experience a positive nitrogen balance. Insufficient quantities of even one essential amino acid is enough to turn an otherwise normal individual into one with negative nitrogen balance.

Define conditional amino acids

Conditional amino acids are amino acids that are synthesized from essential amino acids. This means that if the essential amino acid is not obtained from the diet (deficient) this conditional amino acid will not be able to be synthesized. It will therefore need to be obtained from the diet.

How are amino acids transported into the rest of the body after entering into an enterocyte by PEP1?

Diffusion, facilitated diffusion, or active transport

Define Essential amino acid

Essential amino acids are amino acids that the human body cannot synthesize and therefore, need to be obtained from the diet

What are the 2 sources of amino acids?

Exogenous: from the diet / Endogenous: from the body (synthesized from DNA)

Which 2 AA are converted to alpha KG which is oxidized by TCA cycle?

Glutamate and Glutamine

which 2 AA are produced from one another in reversible reaction requiring folate in kidneys?

Glycine and serine

How do humans get nitrogen?

Humans are unable to obtain nitrogen from the atmosphere, therefore they need to get their nitrogen from food as dietary free amino acids or from bacterial nitrogenases

In general, plant proteins are deficient in what amino acids?

Methionine, Lysine, Tryptophan (MeLT)

What can glutamate from glutamine degradation be used for?

It can be used (in intestines) to make ornithine. *Aspartate is also used in this reaction.

What happens to fumarate?

It is reconverted to aspartate for use in the argininosuccinate synthetase reaction through TCA cycle enzymes (fumarate - yields malate AND malate DH - yields OAA)

What two diseases result from deficient lysine?

Kwashiorkor's Disease, Marasmus Disease

Which AA are ketogenic (2)?

Leucine and Lysine (LL)

Ammoniotelic organisms release nitrogen as?

NH4 and rely on aqueous environments to dilute it

A decrease in the amino acid associated with Hartnup Disorder results in a decrease of ____.

Niacin/B6

Define nonessential/dispensable amino acid

Nonessential/dispensable amino acids are able to be synthesized in the human body (from DNA) ant therefore, an individual does not need to consume these amino acids in order to havethem in the body.

Define transamination

Original amino group is transferred to another a carbon skeleton to form an amino acid, or to an amino acid to have two amino groups

Glutamate --> glutamate Y-semialdehyde--> (aminotransferase/transamination with aspartate) --> _________ ?

Ornithine

What two substrates come together to form citrulline?

Ornithine and Carbamoyl Phosphate

What enzyme catalyzes the reaction to form citrulline?

Ornithine transcarbamoylase

What symptom do patients with Hartnup Disorder experience?

Pellagra Rashes

Complete this chart for breaking down proteins

Pepsinogen HCL or Pepsin Pepsin Stomach Amino acids → peptides / Trypsinogen Enteropeptidase/trypsin Trypsin Intestine Basic Amino Acids → small peptides, free amino acids / Chymotrypsinogen Trypsin Chymotrypsin Intestine Aromatic Amino Acids → small peptides, free amino acids / Procarboxypeptidase Trypsin Carboxypeptidase Intestine Free Amino Acids

What are the 9 essential amino acids?

Phenylalanine, valine, threonine, methionine, tryptophan, histidine, isoleucine, leucine, lysine

How does an excess of ammonia within the body affect the synthesis of GABA?

The increased glutamate will lead to glutamine formation, which depletes glutamate stores (glutamate is neurotransmitter and precursor of GABA). Reduction in brain glutamate affect energy production and neurotransmission.

Define deamination

The original amino group is cleaved but not transferred

Define Kwashiorkor's disease

This occurs in individuals who are getting enough calories to sustain life, however, they are not eating foods that give enough Lysine. An individual would become deficient in Lysine.

Which 4 AA form succinylcholine CoA?

Threonine, methionine, valine, and isoleucine

What is the role of glutamine and alanine?

Transport for ammonia to the the liver by transamination. Alanine is mainly taken by the liver (cori cycle)

In Hartnup Disorder, reduced intestinal absorption and increased renal loss affects which amino acid?

Tryptophan

Which AA are glucogenic and ketogenic (5)?

Tyrosine, Tryptophan, Threonine, Isoleucine, Phenylalanine (TTTiP)

What are the 5 conditionally essential amino acids?

Tyrosine, cysteine, proline, arginine, glutamine

Terrestrial vertebrates take excess NH4+ (ammonia) and convert it into what?

Urea

Arginine can be converted into what two substances?

Urea and Ornithine

How does cerebral edema in infants with hyperammonemia occur?

Urea cycle defects! Increased glutamine levels in the brain lead to increased volume of fluid within glial cells.

What becomes of the amino group after amino acid catabolism?

Urea or Ammonia -----> majority excreted by kidney, minority excreted by intestinal tract.

Vertebrates that convert NH4 to urea are called what?

Ureotelic

Is Urea water soluble?

Yes

When glutamate is transaminated to alpha KG and alanine, where does the alanine go?

alanine will go to liver via portal blood.

What type of enzymes conduct transamination?

aminotransferases or transaminases

glutamine degradation yields what 2 things?

ammonia and glutamate

Hyperargininemia is due to a deficiency in what?

arginase

What is deficient in Argininosuccinicaciduria?

argininosuccinase

What enzyme is deficient in Citrullinemia?

argininosuccinate synthetase

What factors affect the amino acid balance?

dietary intake, how much has been used, availability of food (carbs, lipids), availability of specific AA, need for specific AA

Carbon Skeltons of ketogenic AA can be catabolized for what?

energy in TCA cycle, or converted to ketone bodies or fatty acids. * they cannot be converted to glucose!

What are the functions of histidine?

forms histamine (neurotransmitter), HCL in GI tracts generates carnosine that posses strong antioxidant, anti inflammatory, and anti aging properties.

What is maleylacetoactetae isomerize to?

fumarylacetoactetae

Glucogenic AA are the major carbon source for_______, when glucose levels are low.

gluconeogenesis.

Which AA are important for collecting and eliminating nitrogen via glutamine synthetase and the Urea cycle?

glutamate and aspartate

What enzyme converts glutamate to alpha-keto-glutarate by deamination?

glutamate dehydrogenase

What enzyme deamidated glutamine?

glutaminase

Which is the major AA found in the circulatory system?

glutamine

What enzyme converts glutamate to glutamine by transamidation?

glutamine synthetase

Which 5 AA can be converted in to alpha ketoglutarate?

glutamine, glutamate, Arginine, proline and histidine

Which enzyme is needed for: homogentisate to maleyacteoacetate?

homogentisate oxidase

which enzyme is needed for: hydroxyphenylpyruvate to homogentisate?

hydroxyphenylpyrvate hydroxylase

What two serum aminotransferases are used to indicate tissue damage?

increase in ALT and AST

The products of BCAA are predominantly (glucogenic, ketogenic, both)?

ketogenic

In what organ does the urea cycle take place?

liver, mitochondrial matrix and cytosol

Aminotransferases exist for all amino acids except for what amino acid?

lysine

Where does oxidative deamination of glutamate occur?

mainly in the liver

What enzyme is deficient in Hyperammonemia Type II?

ornithine transcarbamoylase. Similar to type 1 - elevated levels of glutamine in the blood and urine.

Which 3 AA form fumarate?

phenylalanine, tyrosine, apartate

Which enzyme is needed for phenylalanine to tyrosine?

phenylanine hydroxylase

Which enzyme deaminates serine to Pyruvate?

serine DH

What are the functions of glutamine?

source of energy, stimulates GI mucosa cells, prevents gut mucosa atrophy/bacterial translocation, ammonia transport which forms glutamate, some urea production in enterocyte

What can ammonia from glutamine degradation be used for?

synthesis of carbamoyl phosphate (carbamoyl phosphate + ornithine = citrulline which enters portal blood and is taken up by the liver and kidneys)

What is tryptophan used for?

synthesis of: nicotinamide, NADH, serotonin, melatonin

Which enzyme transaminates tyrosine to hydroxyphneylpyruvate?

tyrosine transaminase

degraded arginine forms what?

urea and ornithine, eventually converted to creatine

Is ATP (or GTP) required for the formation of glutamate?

yes