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76 Cards in this Set
- Front
- Back
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What is the precursor to Dopamine?
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Tyrosine -(tyrosine hydroxylase) -> Dopa -(aromatic amino acid decarboxylase +PLP) -> Dopamine.
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What is the precursor to Epinephrine?
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Dopamine -(dopamine hydroxylase) -> Norepinephrine (phenlyethanolamine methlytransferase + adoMet) -> Epinephrine
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What is the precursor to GABA?
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Glutamate -(glutamate decarboxylase)->GABA
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What is the precursor to histamine?
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Histidine-(histidine decarboxylase+PLP)-> histamine
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What is the precursor to Serotonin?
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Trytophan -(tryptophan hydroxylase) ->5-hydroxytryptophan -(aromatic amino acid decarboxylase)-> serotonin
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What is the precursor to Spermine?
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Methionine and ornithine
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What's the product of ornithine decarboxylation?
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Putrescine
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What enzyme is the target for treatment of African Sleeping Sickness? What's the inhibitor used?
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Ornithine decarboxylation. DFMO is the suicide inhibitor that forms a covalent bond with the enzyme
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What are examples of tetrapyrolles?
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hemes, chlorophylls and coenzyme B12
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What are examples of biological amines?
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Neurotransmitters (Dopamine, Norephinephrine, Epinephrine, Serotonin, Histamine) and polyamines (spermine)
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What are tetrapyrroles derived from?
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Delta-aminolevulinate
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What is the precursor molecule of tetrapyrroles?
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Aminolevulinate which is dimerized and then tetramirized
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What does degradation of heme yield
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Biliverdin which is then reduced to bilirubin
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Nucleotide vrs nucleoside
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Nucleoside does not include the phosphates
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Whats the difference between the pentose group of DNA and RNA?
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In RNA there is a hydorxy group at the 2 C position, while DNA just has a hydrogen.
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Where does base attach to pentose in the in pyrimdines?
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N1
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Where does base attach to pentose in the in purines?
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N9
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What are the functions of biological amines?
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They functions as hormones and/or neurotransmitters.
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Which biological amines are derived from tyrosine?
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Dopamine
Norepinephrine Epinephrine |
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Why biological amine comes from tryptophan?
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Serotonin
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Which biological amine comes from histidine?
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Histamine
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Many biological amines are generated decarboxylation of amino acids. How is this accomplished?
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Aromatic amino acid decarboxylase and PLP
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What are Delta-aminolevulinate derived from in animals?
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Sunccinyl-CoA
Glycine |
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What are Delta-aminolevulinate derived from in plants?
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Glutamate
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What inhibits the formation of aminolevulinate?
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Heme
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How do you get tetrapyrroles from aminolevulinate?
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Dimerized to form a heterocycle, which is then tetramized
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Nucleoside adenine
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Adenosine
Deoxyadenosine |
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Nuceloside of guanine
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Guanosine
Deoxyguanosine |
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Nuceloside of cytosine
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Cytidine
Deoxycytidine |
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Nuceloside of thymine
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Thymidine or deoxythymidine
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Nuceloside of uracil
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Uridine
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Nucleotide of adenine
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Adenylate
Deoxyadenylate |
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Nucleotide of guanine
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Guanylate
Deoxyguanylate |
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Nucleotide of cytosine
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Cytidylate
Deoxycytidylate |
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Nucleotide of thymine
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Thymidylate or deoxythymidylate (DNA)
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Nucleotide of uracil
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Uridylate (RNA)
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Basic structure of nucleotides
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Figure 8-1
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In general, what is the difference between nucleotide biosynthesis of pyrimidines vs. purine?
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In purines, bases are built stepwise onto RPPP.
In pyrimidines, a precursos base is synthesized and added to PRPP. |
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How is ribose 5-phosphate activated?
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Addition of the pyrophosphate at the 1' position.
The hydrolysis of pyrophosphate drives the reaction forward. |
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In general, what is the similarity between nucleotide biosynthesis of pyrimidines vs. purine?
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Free bases are NOT synthesized directly and added to PRPP.
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In the purine ring, what nitrogen comes from the amide N of glutamine?
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Figure 22-32
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In the purine ring, what carbons comes from CO2?
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Figure 22-32
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In the purine ring, what carbons comes from formate?
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Figure 22-32
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In the purine ring, what carbons comes from glycine?
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Figure 22-32
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In the purine ring, what nitrogens comes from aspartate?
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Figure 22-32
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What is the primary regulation point purine biosynthesis? What factor acts as negative regulators?
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The transfer of N amide of glutamine to the C1 of PRPP by glutamine-PRPP amidotransferase.
GMP, AMP, IMP |
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IMP
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Inosinate, Branch point between GMP and AMP
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From IMP, the synthesis of GMP uses which NTP as energy source?
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ATP
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From IMP, the synthesis of AMP uses which NTP as energy source?
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GTP
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In pyrimidine ring synthesis, which nitrogen and carbon atoms come from carbamoyl phosphate?
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Figure 22-36
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In pyrimidine ring synthesis, which nitrogen and carbon atoms come from aspartate?
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Figure 22-36
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What pool does carbamoyl phosphate come from?
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A pool distinct from the urea cycle, found in the cytoplasm and synthesized by cytoplasmic CPS II
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What is the pyrimidine ring precursor?
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Orotate
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From the synthesis of orotate to CTP, what other intermediates are required?
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UMP and then, UTP
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What is the commitment step in the synthesis of pyrimidines?
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ATCase forms N-carbamoylaspartate from Asparate and Carbamoyl phosphate
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What regulates ATCase?
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CTP inhibits, while ATP relieves the inhibition.
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What enzyme adds phosphates to nucleosides? What is the source of phosphates?
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nucleoside mono/diphosphate kinase
the source is ATP |
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What enzyme removes the 2 'OH to form dNDP from rNDP?
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Ribonucleotide reductase
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Where are the initial electron carriers donating electrons to ribonucleotide reductase?
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NADPH
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After NADPH, what are the two electron donors to ribonucelotide reductase?
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Thioredoxin
Glutaredoxin |
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What amino acid is reduce in passing electrons to ribonucleotide reductase?
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Cysteine; disulfide bonds are broken down with the addition of electrons.
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What molecule participates in the catalytic subunit of ribonucelotide reductase to transfer of electrons to the 2' OH?
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Tyrosine free radical stabilized by iron atoms
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In general, what are the different levels of regulation in ribonucelotide reductase?
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Regulation at primary regulatory sites
Regulation at substrate specificity sites |
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What are the regulators at the primary regulatory site?
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Positive regulation by ATP (energy charge)
Negative regulation by dATP (feedback) |
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What dTMP synthesized from? What is the enzyme? What molecule acts as a cofactor? What kind of reaction?
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dUMP; thymidylate synthase, THF, one carbon reaction
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Fluorouracil
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Converted FdUMP, which Inhibits Thymidylate Synthase
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Methotrexate
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Inhibits dihydrofolate reductase, blocking regeneration of THF.
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How do glutamine analogs acts as chemotherpeutics? What are example?
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Glutamine analogs inhibit glutamine amidotransferase, which is a commitment step to purine synthesis.
Azaserine and acivicin |
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What is the general strategy for nucleotide degradation?
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1) Removal of 5' phosphate to form the nucleoside
2) Removal of ribose to form the free base |
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What are purines degraded to finally?
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Uric acid
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What are pyrimidines degraded to finally?
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Nitrogens are converted to Urea, while carbons are converted to succ-CoA
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What causes gout?
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Overproduction of uric acid from purine catabolsim
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Salvage pathways
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Allow production of AMP, IMP or GMP from free bases (adenine, guanine, hypoxanthine) combining with PRPP
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What is the product of purine synthesis commitment step?
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5-phosphoribosylamine
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What is the enzyme used in the commitment step of purine synthesis?
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glutamine-PRPP amidotransferase
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What is the product of the pyrimidine commitment step?
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N-carbamoylaspartate
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