Blood, proteins and amino acids

Blood plasma proteins

Proteins found in the liquid medium of blood after the removal of blood cells, synthesized mainly in the liver, and play various roles in the body.

Albumins

A type of blood plasma protein making up about 60% of total plasma proteins, responsible for maintaining oncotic pressure, transporting compounds, and binding drugs.

Globulins

Another type of blood plasma protein making up 36% of total protein amount, comprising different subtypes like alpha, beta, and gamma globulins.

Free amino acid pool

The collection of amino acids in blood plasma derived from food, intracellular breakdown of proteins, and keto-carboxylic acid formation.

Protein metabolism

The process involving the breakdown (catabolism) and synthesis (anabolism) of proteins in the body.

Deamination

The removal of an amino group from amino acids, which can occur directly or indirectly through transamination.

Transamination

The transfer of an amino group from one molecule to another, often involving the conversion of amino acids.

Ammonia detoxification

The process of converting toxic ammonia into urea for excretion from the body.

Nitrogen balance

The equilibrium between nitrogen intake (mainly from proteins) and excretion (mainly as urea, uric acid, and creatinine) in the body, reflecting protein homeostasis.

Oxidative deamination

A process where an amino acid loses an amine group in the form of ammonia.

Transamination

A reaction where an amino group is transferred from an amino acid to a keto acid to form a new amino acid and keto acid.

Pyridoxal phosphate

A coenzyme derived from Vitamin B6, essential for various reactions including transamination and deamination.

Glucose-Alanine cycle

A process linking the production of alanine in muscles to glucose synthesis in the liver, efficient during starvation.

Glucogenic amino acids

Amino acids whose breakdown leads to the production of intermediates that can be used for glucose synthesis.

Ketogenic amino acids

Amino acids whose breakdown leads to the production of acetyl-CoA or acetoacetyl-CoA, used for ketone body synthesis.

Ammonium

Toxic byproduct produced during amino acid deamination, detoxified through various mechanisms including urea synthesis.

Urea Cycle

A series of enzymatic reactions in the liver that detoxify ammonium by converting it into urea for excretion.

Hyperuremia

Condition where blood plasma urea concentration exceeds the normal range.

Hypouremia

Condition where blood plasma urea concentration falls below the normal range.

Hyperammonemia

A condition characterized by high levels of ammonia in the blood, exceeding 47 micromole/L, posing a threat to life due to the inactivation of the Krebs cycle.

Urea Cycle

A metabolic pathway that eliminates toxic ammonia from the body by converting it into urea for excretion.

Glutamate Dehydrogenase

An enzyme involved in catalyzing reactions related to the metabolism of amino acids and the production of ammonia.

Pyrimidine Nucleotide Metabolism

The biochemical processes involved in the synthesis, breakdown, and regulation of pyrimidine nucleotides essential for DNA and RNA synthesis.

De Novo Synthesis

The process of synthesizing complex molecules from simple precursors, such as the production of pyrimidine nucleotides from basic components.

Carbamoyl Phosphate Synthetase

An enzyme involved in the first step of pyrimidine nucleotide synthesis, distinct from CPSI and crucial for the urea cycle and pyrimidine biosynthesis.

Salvage Pathway

A route for recycling nucleotide bases by converting them back into nucleotides, involving specific enzymes like pyrimidine nucleoside phosphorylase and nucleoside kinases.

Feedback Inhibition

A regulatory mechanism in which the end product of a pathway inhibits an enzyme earlier in the pathway, crucial for controlling pyrimidine and purine nucleotide synthesis.

Orotic aciduria

A rare disorder characterized by the excretion of orotic acid in urine due to defective enzymes involved in pyrimidine nucleotide metabolism.

UMP synthase

Enzyme responsible for converting orotic acid to UMP in the pyrimidine synthesis pathway.

Ribonucleotide reductase

Enzyme involved in the reduction of ribose moieties in nucleotides to deoxyribose for DNA synthesis.

Thymidylate synthase

Enzyme that catalyzes the methylation of dUMP to form dTMP in the synthesis of thymidine phosphates.

Deoxyribonucleotides

Nucleotides with a deoxyribose sugar moiety, essential for DNA synthesis.

PRPP synthetase

Enzyme that catalyzes the production of activated 5-phosphoribose-1-pyrophosphate in the priming reaction of de novo purine nucleotide synthesis.

NADPH

Primary reductant required for the reduction of ribose moieties in nucleotides during DNA synthesis.

Salvage pathway

Pathway for the synthesis of purine nucleotides from purine bases, utilizing preformed nucleobases.

Carbamoyl synthetase II

Enzyme involved in the regulation of pyrimidine production in the urea cycle deficiency-induced orotic aciduria.

Thymidine phosphates

Deoxyribonucleoside phosphates essential for DNA synthesis.

De novo synthesis

The process of synthesizing a compound from simple molecules, typically without the aid of biological templates.

Allosteric enzyme

An enzyme that changes its conformation and activity upon binding to a specific effector molecule at a site other than the active site.

Feedback inhibition

The process in which the end product of a biochemical pathway inhibits an earlier step in the pathway to regulate its own production.

Salvage pathway

A pathway in which a compound is regenerated from its degradation products, allowing for the recycling of molecules and conservation of energy.

PRPP (Phosphoribosyl pyrophosphate)

A key molecule in nucleotide synthesis, serving as a precursor for the de novo synthesis of purine and pyrimidine nucleotides.

APRT (Adenine-phosphoribosyl transferase)

An enzyme involved in the salvage pathway of purine nucleotide synthesis, catalyzing the formation of adenine nucleotides.

HGPRT (Hypoxanthine-guanine phosphoribosyl transferase)

An enzyme that plays a crucial role in the salvage pathway of purine nucleotide synthesis, facilitating the formation of guanine and hypoxanthine nucleotides.

Uric acid

The end product of purine metabolism in humans, excreted primarily through urine, with abnormal levels leading to conditions like gout.