Harper's Biochemistry Chapter 31 - Porphyrins & Bile Pigments

An enzyme that plays a role in heme synthesis, a process in which porphyrins are produced.

An intermediate, a molecule that is formed during a chemical process and is then processed further to create something else.

Enzyme catalyzing the reaction to convert 2 molecules of ALA to one molecule of porphobilinogen.

Aminolevulinate, a precursor molecule in heme biosynthesis.

Enzyme catalyzing formation of porphyrin precursors, notably ALA.

Reactants/starting materials needed to form ALA in heme biosynthesis.

A biochemical process creating heme, a crucial component of hemoglobin.

A group of disorders resulting from inherited mutations in genes regulating heme synthesis.

Acquired condition impacting heme synthesis, inactivating crucial enzymes.

A group of genetic disorders affecting heme synthesis, leading to the accumulation of porphyrin precursors in body tissues.

The metabolic pathway that produces heme, a crucial component of hemoglobin.

A hallmark of porphyrias, these porphyrin precursors build up in body tissues, causing symptoms.

Intermediate molecules in porphyrin metabolism, their accumulation can cause issues.

The daily breakdown and recycling of red blood cells, releasing heme components.

Increased sensitivity to light, sometimes seen in porphyrias, due to the abnormal accumulation of porphyrin precursors

Genetic variations can cause abnormalities in enzymes involved in porphyrin synthesis, affecting the whole process.

The breakdown of heme, resulting in the production of bilirubin.

Heme c has covalent thioether links to an apoprotein, unlike heme b which easily dissociates from the apoprotein.

Jaundice is caused by high bilirubin levels in the blood, either from overproduction or excretion failure.

Porphyrins are cyclic compounds made from four pyrrole rings linked by methyne bridges, with potential side chains replacing hydrogen atoms.

Heme synthesis starts with Succinyl-CoA and Glycine.

Heme proteins are widely found in nature, with vertebrate proteins typically binding one heme c molecule per protein and invertebrate ones potentially binding more.

Porphyrins can form complexes with metal ions.

Proteins that contain heme are widely distributed in nature, and vertebrates generally bind one heme c per mole.

A process that creates heme, a vital component for many proteins like hemoglobin.

A protein in red blood cells that carries oxygen.

A protein that stores oxygen in muscles.

A protein involved in the electron transport chain.

A protein that helps process foreign substances.

A protein that breaks down hydrogen peroxide.

An enzyme involved in tryptophan breakdown.

The process of creating heme from succinyl-CoA and glycine.

The regulatory enzyme in heme biosynthesis, its activity increases with low heme levels.

A waste product formed from bilirubin in the intestines, detectable in urine.

A byproduct of red blood cell breakdown, processed in the liver and excreted in bile.

Jaundice caused by blocked bile ducts, preventing bilirubin from reaching the intestines.

Jaundice resulting from increased red blood cell destruction, leading to higher urobilinogen levels.

Inherited disorders due to enzyme defects in heme biosynthesis.

Another enzyme in heme synthesis, not regulated by heme levels.

High levels of urobilinogen in the urine, suggesting increased red blood cell breakdown (hemolysis).

A precursor molecule in heme biosynthesis, containing four propionic acid substituents.

The removal of a carboxyl group (-COOH) from a molecule.

A porphyrinogen intermediate formed from uroporphyrinogen III after decarboxylation.

Enzyme catalyzing the conversion of uroporphyrinogen III to coproporphyrinogen III.

Colorless intermediate molecules in heme synthesis.

Chemical linkages (-CH=), formed in the porphyrin structure, between pyrrole rings.

The metabolic pathway creating heme from precursors.

A porphyrinogen intermediate in the heme synthesis pathway, converting to protoporphyrin.

The final porphyrin precursor in heme biosynthesis, containing specific substituents.

An enzyme involved in the heme synthesis pathway, specifically in the conversion of coproporphyrinogen III.

A genetic disorder affecting heme synthesis, characterized by the accumulation of coproporphyrin precursors, causing photosensitivity and abdominal pain.

An enzyme in the heme biosynthesis pathway, responsible for the conversion of protoporphyrinogen to protoporphyrin.

A genetic porphyria impacting heme biosynthesis, leading to the accumulation of specific porphyrin precursors and symptoms like photosensitivity and abdominal pain.

Enzyme in the heme biosynthesis pathway, crucial for incorporating iron into protoporphyrin IX to form heme.

A genetic porphyria impacting heme biosynthesis, leading to the accumulation of protoporphyrin, causing photosensitivity.

An increased sensitivity to sunlight or ultraviolet radiation due to an abnormality in the heme synthesis pathway.

Elevated levels of δ-aminolevulinic acid (ALA) and porphobilinogen (PBG) in the urine, indicative of certain porphyrias.

Elevated levels of coproporphyrin III in the feces, often observed in some porphyrias during active stages.

An elevated level of protoporphyrin IX in the feces is a marker for some porphyrias.

Elevated levels of protoporphyrin IX within red blood cells, a characteristic finding during the active phases in some porphyrias.

Porphyria treatment focuses on managing symptoms, avoiding drugs increasing cytochrome P450 production, limiting carbohydrate intake, and using antibiotics to adjust bilirubin levels.

Bilirubin detachment and tissue absorption occurs after binding to albumin, with antibiotics also playing a part.

Bilirubin is taken up by cells, binding to cytosolic proteins to prevent its re-entry into the bloodstream.

Bilirubin, initially nonpolar, is converted to a more water-soluble form through conjugation with glucuronic acid.

The process where the liver moves bilirubin from the blood into bile.

Water-soluble form of bilirubin, processed by the liver, crucial for excretion.

Lipid-soluble form of bilirubin, not ready for excretion, can cross the blood-brain barrier.

Yellowing of the skin and eyes, caused by bilirubin buildup in the blood.

Obstruction of bile ducts causes bilirubin to build up in the blood, leading to jaundice.

High levels of bilirubin in the blood, leading to conditions like jaundice.

Byproduct of bilirubin breakdown in the intestines, detectable in urine (choluric jaundice).

Fluid produced by the liver, containing bile salts and bilirubin. Crucial for fat digestion.

The process of creating heme, a crucial component of hemoglobin, starting with succinyl-CoA and glycine.

The regulatory enzyme in heme biosynthesis, its activity changes with heme levels.

A waste product formed from bilirubin in the intestines, detectable in urine.

A byproduct of red blood cell breakdown, processed in the liver and excreted in bile.

Jaundice caused by blocked bile ducts, preventing bilirubin from reaching the intestines.

Jaundice resulting from increased red blood cell destruction, leading to higher urobilinogen levels.

Inherited disorders due to enzyme defects in heme biosynthesis, leading to the accumulation of porphyrin precursors.

High levels of urobilinogen in the urine, suggesting increased red blood cell breakdown (hemolysis).

Heme c differs from heme b by having covalent thioether links to an apoprotein, preventing its easy dissociation.

Heme b is easily dissociated from its apoprotein

Cyclic compounds formed from four linked pyrrole rings via methyne bridges. Side chains may replace some hydrogen atoms.

Heme synthesis begins with succinyl-CoA and glycine.

Elevated bilirubin levels in the blood, resulting from overproduction or excretion failure.

Heme proteins are widespread in nature, with vertebrates typically binding one heme c per protein.

Heme synthesis occurs in both the cytosol and mitochondria.

An inherited condition where the enzyme ALA synthase 2 is not functioning properly, leading to issues in heme synthesis and potentially anemia.

A genetic condition characterized by an impaired ALA dehydratase enzyme, leading to the accumulation of porphyrin precursors, resulting in abdominal pain and neuropsychiatric symptoms.

A genetic disorder affecting heme synthesis and causing attacks of abdominal pain and neurologic problems linked to the enzyme Uroporphyrinogen I synthase deficiency.

A genetic disorder causing the build-up of abnormal porphyrins in red blood cells, leading to sensitivity to light.

A genetic disease associated with a defect in the enzyme Uroporphyrinogen decarboxylase, causing sensitivity to sunlight and skin lesions.

Quantitative assays of suspected defective enzymes are crucial for diagnosing genetic porphyrias.