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DM Lecture 28: 1-Carbon Metabolism and some Products of Amino Acids
Terms in this set (48)
Catecholamine signaling molecules are derived from what AA?
What are the 3 steps involved in the formation of Dopamine?
1- Phenylalanine --> Tyrosine
2- Tyrosine --> L-Dopa
3- L-Dopa --> Dopamine
What are the 2 steps involved in the conversion of Dopamine to Epinephrine?
1- Dopamine --> NE
2- NE --> Epi
What is the Enzyme and co-factor involved in the conversion of Phenylalanine to Tyrosine?
What is the Enzyme and co-factor involved in the conversion of Tyrosine to L-Dopa?
What is the Enzyme and co-factor involved in the conversion of L-Dopa to Dopamine?
PLP (Vitamin B6)
What is the Enzyme and co-factor involved in the conversion of Dopamine to Norepinephrine?
What Enzyme and Co-factor involved in the conversion of Norepinephrine to Epinephrine?
Dopamine Beta- Hydroxylase
In the first step involved in the formation of Serotonin- Tryptophan is converted to .....? What enzyme catalyzes it and what cofactor is required?
What is 5 hydroxytryptophan converted to? What enzyme and co-factor is required?
5-Hydroxy Tryptamine aka Serotonin
Amino acid decarboxylase
PLP (Pyridoxal phoshpate)
5-Hydroxy Tryptamine aka Serotonin can then be converted to ..... after some modifications? It can also be broken down by .... to form .... thus it can be used to measure Serotonin levels in Urine?
5-HIAA (5-hydroxyindole acetic acid)
The Co-enzyme Tetrahydrobiopterin (BH4) is required for what 3 reactions?
1- Phenylalanine hydroxylase (converts Phe to Tyr)
2- Tyrosine hydroxylase (converts Tyr to DOPA)
3- Tryptophan hydroxylase (converts Trp to 5-hydroxy tryptophan)
PKU II (Malignant PKU) is a condition that occurs as a result of by a deficiency of ...... synthesis or by the deficiency of .... ? These deficiencies results in elevated levels of ....?
The enzyme Dihydrobiopterin Reductase functions in reducing Dihydrobiopterin (BH2) to form ....?
Since Phenylalanine cannot be converted to Tyrosine in patients with PKU II (deficiency of BH4) it is instead converted to ....... which is excreted in the urine and thus is the reason for the characteristic ..... odor of the urine?
•Phe is metabolized to phenylpyruvate, phenylacetate & phenyllactate (excreted in urine) resulting in mousey odor of urine
PKU II develops much more severe ..... symptoms as compared to Classical PKU (PKU I) ? It also results in decreased .... and ..... production?
Catecholamine (dopamine, norepinephrine, epinephrine)
Treatment for PKU II include dietary ..... restriction and providing dietary ...... ? Treatment also includes ...... as a structural analogue of BH4?
Deficiency of Dihydrobiopterin synthesis or dihydrobiopterin reductase results increased levels of ...... & decreased synthesis of ....?
Neurotransmitters (catecholamines, serotonin)
- catecholamines, serotonin
S-Adenosyl methionine (SAM) is synthesized from .....?
It is a Methyl group donor in the synthesis of ..... and ......?
It serves in formation of .......
It also causes methylation of ..... and .....?
Choline (Phosphatidylcholine, and acetylcholine)
DNA and Histone
After donating its Methyl group, SAM is converted to ....?- this can have 2 fates- its either converted to ...... which requires .... or its converted back to ...... - requires ..... and ......?
PLP (Vitamin B6)
What are the 3 Amino acid 1-C unit sources incorporated into Tetrahydrofolate (BH4) that form the 1-C pool?
..... and ...... are used as 1-carbon donors for synthesis of .... and ...., which are necessary for .... and ..... synthesis?
DNA and RNA (cell division)
...... is used in the conversion/recycling of Homocysteine to .....? This conversion also requires .....?
-Can be considered the "storage" form of THF but not able to function in most reactions
-Only participates in one reaction which is this one!!!!
Vitamin B12 (Cobalamine)
....., which is made from ......., is needed in the conversion of Homocysteine to methionine.
In the conversion Methyl-THF catalyzed conversion of Homocysteine to Methionine an empty .... is given off which can reenter the ..... pool?
-Traps the THF in the cell
-Methylene THF -> Methyl THF is IRREVERSIBLE
THF is now "empty" and it may now reenter the pool of available 1-C carriers by accepting a 1-C group from an amino acid
A deficiency of Folate can lead to reduction in the .... donors resulting in reduced synthesis of ..... and ..... which leads to delays in .... synthesis resulting in reduced rates of cell division?
Purines and Pyrimidines
Folate deficiency can also lead to abnormal formation of ........ and decreased ..... concentration?
- Macrocytes and Megaloblasts are observed in blood smears
Decreased Hemoglobin concentration as a result of Folate deficiency can lead to ..... and ...... anemia?
In a Peripheral blood Smear of WBCs Folate deficiency can cause formation of ..... neutrophils?
Blood smear in patients with Folate deficiency and ..... deficiency are similar?
Case report: Folic acid deficiency
The richest sources of Folate are ......?
Green Leafy Vegetables
Folate deficiency during Pregnancy (preconception & first month of conception) is associated with a high risk of ...... defects in the fetus?
What are the high risk groups for folate deficiency?
Neural tube (eg: Spina bifida)
Folate deficiency can be present in high risk groups:
•Persons who avoid vegetables in the diet
Folate deficiency may be diagnosed with the ..... test?
In the Histidine load test the conversion of Histidine to ..... and then to ........ requires ...... thus if there is low or absent levels of Folate high levels of ..... levels will be found in the urine thus indicating a Folate deficiency?
- in the presence of Folate FIGLU is converted to Glutamate
Case report: Vitamin B12 deficiency
Vitamin B12 deficiency is characterized by the occurrence of ...... and the presence of ..... features?
eg: Tingling sensation in the hands and feet, inability to walk, psychiatric disturbances, urinary incontinence etc
.... released from ....... cells of the stomach bind to Vitamin B12 and is required for Vitamin B12 absorption?
Vitamin B12 is absorbed in the ...... as a complex of B12 and the intrinsic factor
The Main sources of Vitamin B12 are .... sources?
- a deficiency of Vitamin B12 might be seen in vegans
What are the 2 enzymes/reactions that require Vitamin B12 as a co-factor?
1- Conversion of Homocysteine to Methionine via Methionine synthase (also requires methyl THF)
2- Conversion of Methylmalonyl CoA to Succinyl CoA via Methylmalonyl CoA Mutase
Patients with Vitamin B12 deficiency have increased levels of .... in circulation as well as increased urinary levels of .....?
Elevated ....... levels are present in both ....... and ........ and therefore, cannot be used to distinguish between the two!
Methylmalonic acid (Methylmalonate)
Methylmalonic acid (Methylmalonate)
Vitamin B12 deficiency
Patients with Vitamin B12 deficiency also have deficiency of the usable form of ....?- this is known as ....?
In B12 deficiency, folate levels might be normal or high, but the folate is not usable because it is in the methyl-THF form
In Vitamin B12 deficiency Folate is trapped as ....?- this cannot be converted back to other forms of .... and thus is an irreversible reaction and as a result other forms of .... become deficient resulting reduction in reduced .... and ..... synthesis which leads to reduced rates of ...... which can cause ....?
Purine and Pyrimidine (Thymidine)
Ineffective DNA synthesis as a result of Vitamin B12 deficiency can lead to ......? Inadequate Myelin synthesis as a result of Vitamin B12 deficiency can lead to .... damage? Hyperhomocysteinemia as a result of Vitamin B12 deficiency can lead to ...... disease?
-SAM deficiency since sam is made from methionine, if homocysteine can't be converted back to methionine due to vitamin B12 deficiency, then we can't make sam
Risk factors for developing a deficiency of Vitamin B12 include being strict .... and/or by the occurrence of Atrophic ..... , ...... anemia or by a disease of the ....?
Gastritis (loss of parietal cells)
Pernicious (autoimmune destruction of parietal cells)
Ileum (tuberculosis, Crohn's disease)
Summary of metabolic roles of vitamin B12 and folic acid
Compare and contrast Folate deficiency vs Vitamin B12 deficiency
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