Harper's Biochemistry Chapter 28 - Catabolism of Proteins & of Amino Acid Nitrogen

A metabolic pathway that converts ammonia into urea, a less toxic form of nitrogenous waste, allowing for its excretion.

Enzyme that initiates the urea cycle by converting ammonia, bicarbonate, and ATP to carbamoyl phosphate, a key reactant.

An allosteric activator of Carbamoyl Phosphate Synthetase I, regulating the urea cycle's activity.

A non-protein amino acid that's a critical intermediate in the urea cycle.

An intermediate in the urea cycle, formed by the reaction of carbamoyl phosphate and ornithine.

Enzyme that links citrulline and aspartate to form argininosuccinate, using ATP.

An intermediate in the urea cycle, formed from the combination of citrulline and aspartate, before being further processed.

The urea cycle involves ATP, impacting energy expenditure in the cells.

Starvation can increase the levels of urea cycle enzymes to deal with increased ammonia production.

Rare genetic disorders affecting urea cycle enzymes, leading to toxic ammonia buildup.

A cyclic process in mammals that uses six enzymes to produce urea from ammonia, aspartate, and carbon dioxide.

A byproduct of protein and amino acid breakdown, which is toxic and needs removal from the body.

An enzyme that initiates the synthesis of urea by combining carbon dioxide, ammonia, and ATP.

The major nitrogenous waste product in humans, excreted in urine.

The maintenance of a stable pH in the body, influenced by ammonia excretion.

A key intermediate in the urea cycle, regenerated at the end of the process without net loss.

An amino acid crucial to the production of urea, also an intermediate in the cycle.

Muscle releases branched-chain amino acids, like valine, primarily utilized by the brain.

Alanine is a crucial amino acid for the liver's glucose production. It's more effective at this than other amino acids.

The liver's ability to make glucose from alanine doesn't become maxed out until alanine levels are significantly higher than normal.

These amino acids play a vital role in nitrogen metabolism, released during protein-rich meals. Muscle and peripheral tissues extract them.

Urea synthesis happens in four steps: transamination, oxidative deamination, ammonia transport, and urea cycle reactions.

A reaction that moves nitrogen from one amino acid to a keto acid (like alpha-ketoglutarate), creating glutamate.

Metabolic pathway converting ammonia to urea for excretion.

Genetic disorders impacting metabolic enzymes.

Powerful technique for screening newborns for metabolic disorders.

Testing newborns for metabolic diseases in the USA.

Metabolic disorders affecting organic acid metabolism.

Metabolic disorders involving amino acid metabolism.

Metabolic problems in breaking down fatty acids.

Proteins controlling the steps of the urea cycle.

Adjusting diet to aid in managing metabolic diseases.

A metabolic pathway that removes ammonia from the body by converting it into urea, which is less toxic than ammonia.

The enzyme that starts the urea cycle, combining ammonia and carbon dioxide to form carbamoyl phosphate using ATP.

A molecule that activates the enzyme Carbamoyl Phosphate Synthetase I, speeding up the urea cycle.

A molecule that releases urea by breaking itself down, regenerating the cycle's intermediate.

A central intermediate in the urea cycle; it's regenerated without net loss during the cycle.

The urea cycle requires the use of 2 ATPs to efficiently remove nitrogenous waste.

The enzyme that breaks down arginine to release urea and regenerate ornithine, a critical step in urea cycle.

Muscles release branched-chain amino acids (like valine) which are primarily absorbed by the brain.

Alanine is a crucial amino acid for the liver to make glucose, and it's more efficient than other amino acids in this process.

The liver's ability to produce glucose from alanine doesn't reach maximum capacity until alanine levels are significantly raised.

Amino acids that play a major role in nitrogen metabolism. Released during protein-rich meals, muscle and peripheral tissues absorb them.

Urea synthesis happens in four steps: transamination, oxidative deamination, ammonia transport, and urea cycle reactions.

A reaction that moves nitrogen from one amino acid to a keto acid, creating a different amino acid (like glutamate).

A reaction that moves nitrogen from an amino acid to a keto acid, creating a new amino acid and a new keto acid.

The body's process of eliminating ammonia, a harmful byproduct of protein breakdown, by converting it to urea.

A metabolic pathway that converts ammonia into urea, a less toxic form, for excretion.

A vitamin B6 derivative that acts as a carrier for amino groups during transamination.

A life-threatening condition resulting from high ammonia levels in the blood.

Enzyme that initiates the urea cycle, combining ammonia, carbon dioxide, and ATP to form carbamoyl phosphate.

Major nitrogenous waste product in humans, excreted in urine.

Argininosuccinate is broken down into arginine and fumarate by argininosuccinase.

Similar symptoms can result from different gene mutations affecting enzymes in a metabolic pathway.

Treatment for metabolic disorders is based on the biochemistry of normal and impaired pathways.

Identifying accumulating intermediates helps pinpoint the faulty metabolic step.

Measuring the enzyme's function provides a definite diagnosis.

Comparing patient DNA to normal DNA identifies the specific gene mutation.

Enzyme initiating urea production, needing N-acetylglutamate for its function.

A reaction that moves a nitrogen group from one amino acid to an alpha-keto acid, often creating glutamate.

Ammonia is harmful; the body must convert it to a less toxic form for removal.

Metabolic pathway removing ammonia by converting it to urea for excretion.

Starts the urea cycle, combining ammonia, carbon dioxide, and ATP to form carbamoyl phosphate.

The major nitrogenous waste product in humans, primarily excreted in urine.

Enzyme catalyzing the reversible oxidation of glutamate to α-ketoglutarate, using NAD(P)+ as an oxidoreductant.

An intermediate in the citric acid cycle and a receptor for amino groups during transamination.

A coenzyme important in transamination reactions.

A rare metabolic disease caused by defects in carbamoyl phosphate synthetase I.

Enzyme creating N-acetylglutamate, a component vital for carbamoyl phosphate synthetase I activity in the urea cycle.

Metabolic diseases stemming from deficiencies in urea cycle enzymes, resulting in ammonia buildup.

High levels of ammonia in the blood, a dangerous symptom of urea cycle deficiencies.

Enzyme initiating the urea cycle.

Inherited conditions affecting metabolic enzymes like urea cycle enzymes.

Dangerous condition caused by excessive ammonia in the blood.

The continuous exchange of amino acids between organs like the liver and muscles to maintain stable blood levels.

Alanine plays a key role in transferring nitrogen from muscle to liver during post-absorptive conditions.

Maintaining consistent amino acid concentrations in the blood is essential, regulated by exchanges between sources and sinks.

Muscle releases amino acids, especially alanine, into the bloodstream during periods between meals.

The liver plays a critical part in taking up amino acids from the bloodstream for various metabolic processes, notably gluconeogenesis.

The liver's process of producing glucose from amino acids, like alanine, when needed.

The period after digestion when the body relies on stored nutrients and internally produced glucose, instead of food.

Animals excrete excess nitrogen as ammonia, uric acid, or urea, depending on their environment and physiology.

Aquatic animals like fish excrete ammonia, which is easily eliminated in water.

Birds excrete uric acid, conserving water and maintaining low weight.

Humans excrete urea, a less toxic and water-soluble nitrogenous waste.

A cycle where alanine is made in muscle and converted back to glucose in the liver.

Alanine is created in muscles by transamination from glucose-derived pyruvate.

Alanine is crucial for the liver to produce glucose.

A reaction that moves a nitrogen group from an amino acid to a keto acid, creating a different amino acid.

Removal of an amine group from an amino acid to produce ammonia, often using oxidative reactions.

An amino acid central to amino group transfer and ammonia production.

Toxic nitrogenous waste product of protein metabolism.

A metabolic pathway that converts ammonia into urea for excretion.

A less toxic form of nitrogenous waste excreted in urine.

Enzymes that catalyze transamination reactions; are specific to substrate pairs.

Specific aminotransferase that catalyzes the transfer of amino groups to pyruvate, forming alanine

L-Glutamate dehydrogenase facilitates the reversible conversion of glutamate. May use NAD+ or NADP+ to do so.

The continuous breakdown and synthesis of proteins in the body.

The average speed at which proteins are broken down and rebuilt in healthy individuals.

Some proteins break down faster than the average rate.

Protein breakdown that requires energy in the form of ATP.

Protein breakdown that doesn't rely on a direct energy source like ATP.

A cellular structure involved in protein breakdown.

A protein that tags other proteins for degradation by the proteasome.

Structures on the cell surface that mediate the removal of proteins.

Cellular organelles containing enzymes for breaking down proteins.

How mammals break down nitrogenous waste.

How birds and fish handle nitrogenous waste differently from mammals.

Enzymes transferring amino groups.

Enzyme that catalyzes glutamate's oxidation.

Enzyme catalyzing the removal of ammonia from glutamine.

The main nitrogenous waste product in mammals.

The metabolic pathway that converts ammonia to urea.

Genetic mutations that cause issues in metabolic pathways.

Testing newborns for metabolic conditions.

A technique to diagnose metabolic diseases in newborns.