Porphyrins and Hemoglobins Flashcards
True or False: Hemoglobin and myoglobin are chemically similar molecules that contain porphyrin groups.
True.
Porphyrins are cyclic structures comprised of four pyrrole rings joined by methane bridges
The chelation of ferrous iron to protoporphyrin produces what?
heme
Heme
the prosthetic group of hemoglobin responsible for binding oxygen
Porphyrias
a group of rare disorders that result from disturbances in heme synthesis
–
refers to a group of rare disorders that result from a buildup of natural chemicals called porphyrins in the body. Porphyrins are needed to make heme, a part of hemoglobin. Hemoglobin is a protein in red blood cells.
True or False: Analysis of porphyrins occurs in the lab
True
Hemoglobin molecules are designed to ___, ___, and release oxygen
bind, deliver
***Hemoglobinopathies
are disorders that have qualitative defects in the hemoglobin molecule
**Thalassemias
are quantitative defects in the production of hemoglobin molecules
is an inherited blood disorder that causes your body to have less hemoglobin than normal.
This is a simple heme protein found in cardiac and skeletal muscles
Myoglobin
These are chemical intermediates in the synthesis of hemoglobin myoglobin, and other respiratory pigments called cytochromes, what are they?
Porphyrins
Iron is chelated to what to form heme?
the porphyrin ring
Porphyrins are analyzed to aid in the diagnosis of what?
porphyrias: diseases that result from disturbances in heme synthesis
True or False: excess amounts of the intermediate compounds in blood, urine, or feces indicate a metabolic block in heme synthesis
True
–
So if you have too many intermediates, it means that something has gone wrong in the system
These reduces compounds that are intermediates in the biosynthesis of heme (the non-protein, iron-containing prosthetic group of hemoglobin).
They oxidized on exposure to air to porphyrins
Porphryinogens
Isomers
substitution of the pyrrole rings that make up the porphyrinogen macrocycle generate 4 isomers for every porphyrin compound
***Which types of isomers occur naturally?
-Type I and Type III
Which type of Isomer is the only one to form heme
Type III
In some disorders, which type of isomer in the non-functional state may be found in excess in body fluids and tissue?
-Type I isomers
Porphyrin are Photoactive due to extensive conjugation of the ___________ ring
tetrapyrrole
so that 4 sided ring
What color do Porphyrins show off?
Dark red color
due to strong absorbance in the visible region of the spectrum
Porphyrins absorb light of 400 nm wavelength and emit a characteristic orange-red fluorescence between ___________
600-650 nm
–
And a lot of time you will see that in urine
True or False: Aqueous solubility of porphyrins varies with the number of carboxylic acid substituents present in the partilcular porphyrin compounds
True
The solubility of porphyrins depends on how many groups it has.
**Uroporphyrin (Uro) has _____ carboxylic groups, so it’s soluble in what?
8
It is the most soluble in water! It’s excreted in urine.
Coproporphyrin (Copro) has ____ carboxylic acid constituents, intermediate solubility found in _____, _____ , ___
4, blood, urine, feces
Porphyrins with only ___ carboxyl groups are the least soluble
two
Why do we care about solubility?
Solubility influences what?
Solubility influences the type of specimen selected for measurement of particular porphyrin intermediates
–
If you have Porphyrin with only 2 carboxyl groups, you are not going to be able to look for it in the urine. It’s going to affect the sample your going to get for that issue.
True or False: All cells contain hemoproteins and can synthesis heme.
True.
but done mainly in bone marrow and liver
What are the two primary sites for heme synthesis?
The bone marrow and liver.
What is accomplished by a sequence of reactions catalyzed by 8 different enzymes?
Biosyntheis
*****One molecule of heme is produced from 8 molecules of what?
ALA - ( delta- aminolevulinic acid)
***In the last step of biosynthesis ( Syntheis of Heme) requires what to bind on to Protoporphyrin to get to heme?
Iron (Fe2+)
**If there is any issue with any of the steps of the Synthesis of Heme, it is due to what?
Porphyria
There is a Porphyria that correlates to every single one of those steps.
The first and the last 3 synthetic reactions in Biosynthesis requires how much energy?
Where do they take place? Where do the rest take place?
-a lot of energy
-They take place in the Mitochondria.
- The rest take place in the Cytosol.
In the synthesis of heme: each reaction is catalyzed by a particular ______.
enzyme
Heme formation is regulated by what kind of feedback?
negative
–
like most things in the body.
Control rate of heme in the liver is through regulation of which enzyme?
ALAS (delta-aminolevulinic acid) synthase
Increases in the pool of hepatic heme diminishes the production of what enzyme?
ALAS
–
because it is a negative feedback, so if you have a lot of heme, you don’t need that ALAS there to make more. But you get more production if heme is low.
ALAS production is increased when what is depleted/low?
heme
In bone marrow erythrocytes, do ALA control the rate of heme synthesis?
No, other enzymes in the pathway and the rate cellular iron uptake seem to control of the rate of heme synthesis.
Most diseases are ________ ____ with 50% reduction in activity of the affected enzyme
autosomal dominant
–
autosomal dominant is one of many ways that a trait or disorder can be passed down through families.
Excessive accumulation and excretion of intermediate compounds that produce particular symptoms are due to what?
Enzyme defects
–
So it’s where ever it was stopped on that cascade, is going to determine what kind of symptoms a person will have.
What are Neuropsychiatric symptoms?
What can they tell us about heme synthesis?
abdominal pain, nauseas, constipation, hypertension, PSYCHIATRIC symptoms, fever, paresthesia
These are excess of the early precursors in the pathway of heme synthesis (ALA, PBG)
–
paraesthesia is the term for sensation of tingling, during, pricking or prickling, skin-crawling, itching, “pins and needles” or numbness on or just underneath your skin.
What are the Pophryias that go along with Neuropsychiatric symptoms are
-ALA dehydrates deficiency porphyria (ADP)
-Acute intermittent porphyria (AIP)
What are typical Cutaneous symptoms of disorders of heme biosynthesis ?
What are the cause of Cutaneous symptoms?
photosensitivity, blisters, excess facial hair, hyperpigmentation
The cause is excess of porphyrin intermediates
What are the Porphyrias that are seen with Cutaneous symptoms?
-CEP (Congenital erythropoietic porphyria)
-PCT (Porphyria cutanea tarda)
-EPP (Erythropoietic portoporphyria)
-XLPP (E-linked protoporphyria )
With the Cutaneous symptoms, you get an increased fragility of light-exposed skin in which Porphyrias?
CEP and PCT
(congenital erythropoietic porphyria & Porphyria cutanea tarda)
**You get a Burning of light-exposed skin in which Porphyrias?
EPP and XLPP
(Erythropoietic protoporhyria and X-linked protoporphyria)
True or False: Photosensitizing effects of the porphyrins are attributed are attributed to absorption of light
True
–
So there is something going on in your skin. Fun fact this might be the reason for the legends of vampires, because if they go outside they burn .