Term
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Definition
| heme-containing monooxygenases, aka mixed-function oxidases, that act on steroids, fatty acids and xenobiotic compounds. |
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Term
| Nitric oxide synthases are |
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Definition
| cytochrome P450-like enzymes with varied activities |
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Term
| LOCATIONS OF CYTOCHROMES P450 |
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Definition
| Endoplasmic reticulum or microsome (e.g.,in liver) and mitochodrion (e.g., in adrenal cortex). |
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Term
| REACTION OF CYTOCHROMES P450 |
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Definition
| NADPH + H+ + O2 + SH -> NADP+ + H2 O + SOH |
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Term
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Definition
| is the terminal component of an electron transport chain |
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Term
| The role of the assembly of CYTOCHROMES P450: |
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Definition
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Term
| FUNCTIONS CYTOCHROMES P450: |
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Definition
1. Production of steroid hormones
2. Metabolism of fatty acids and their derivatives
3. Inactivation or activation of xenobiotics, e.g., drugs, food additives, environmental pollutants.) |
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Term
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Definition
| increases the solubility and facilitates the excretion of the substrate |
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Term
| Hydroxyl groups provide______which is often important in___________ |
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Definition
sites for conjugation
the detoxification of xenobiotic compounds |
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Term
| enzymes in mammals are encoded by |
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Definition
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Term
| Humans have over ___ genes that encode P450 enzymes |
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Definition
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Term
| Generally _______and ______ are used instead of _____ and _____. |
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Definition
“forms”
“isoforms”
“enzymes” and “isozymes” |
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Term
Many cytochromes P450 are induced by ________
The induction may occur at _________ |
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Definition
by endogenous or exogenous compounds
either the transcriptional or posttranscriptional level. |
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Term
| Induction pathway of CYP1A1 and CYP1A2 |
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Definition
Binding of polycyclic aromatic hydrocarbon (PAH)to cytosolic aryl hydrocarbon (ah) receptor ->
Translocation of PAH-ah receptor
complex to nucleus->
Binding of PAH-ah receptor complex to
ah receptor nuclear translocator (Arnt)->
Binding of above assembly to specific
responsive element on DNA->
Transcription of CYP genes |
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Term
| alcohol consumption induces |
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Definition
| the microsomal ethanol oxidizing system (MEOS), e.g., CYP2E1 |
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Term
in Chronic alcohol consumption cytochrome P450 will convert _________to ______
Leading to ________ |
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Definition
| acetaminophen to toxic metabolites, e.g., N-acetyl-p-benzoquinoneimine (NAPQI), leading to liver cell damage |
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Term
| __________has been reported in chronic alcoholics upon administration of__________ |
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Definition
Hepatotoxicity
therapeutic doses of acetominophen |
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Term
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Definition
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Term
| Metabolism of ethanol in non-alcoholics: |
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Definition
1. Ethanol -> acetaldehyde
2. Acetaldehyde -> acetate
3. Acetate -> acetyl-CoA |
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Term
| Step 1 of Metabolism of ethanol in non-alcoholics: |
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Definition
Ethanol -> acetaldehyde
Enzyme: Alcohol dehdrogenase
Location:Liver cytosol
Reaction:Ethanol + NAD+acetaldehyde + NADH + H+ |
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Term
| Step 2 of Metabolism of ethanol in non-alcoholics: |
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Definition
Acetaldehyde -> acetate
Enzyme: Acetaldehyde dehydrogenase
Location:Liver mitochondrion
Reaction: Acetaldehyde + NAD+ + H2O acetate + NADH + H+ |
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Term
| Step 3 of Metabolism of ethanol in non-alcoholics: |
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Definition
Acetate -> acetyl-CoA
Enzyme: Acetyl-CoA synthetase
Location:Muscle cytosol or mitochondrion
Reaction: Acetate + ATP + CoASH acetyl-CoA + ADP + Pi |
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Term
| Chronic consumption of large amounts of alcohol induces |
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Definition
| the microsomal ethanol oxidizing system (MEOS) in the liver |
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Term
| MEOS oxidizes a significant amount of the alcohol as follows (Metabolism of ethanol in alcoholics) |
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Definition
Ethanol -> acetaldehyde
Enzyme: MEOS
Location:Liver endoplamic reticulum
Reaction: Ethanol + NADPH + H+ + O2 -> acetaldehyde + NADP+ + 2H2O |
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Term
| The microsomal (endoplasmic reticulum) system (liver) |
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Definition
| NADPH -> [ FAD -> FMN]* -> CYP |
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Term
In NADPH -> [ FAD -> FMN]* -> CYP
what does the "*" denote |
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Definition
*This represents the enzyme “NADPH-cytochrome P450
reductase” or simply “cytochrome P450 reductase”. |
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Term
what may also participate in this electron transport system:
NADPH -> [ FAD -> FMN]* -> CYP |
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Definition
| Cytochrome b5 and NADH-cytochrome b5 reductase |
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Term
| The mitochondrial system (adrenal cortex) |
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Definition
| NADPH -> [FAD]* -> [FeS]** -> [FeS]** -> CYP |
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Term
in NADPH -> [FAD]* -> [FeS]** -> [FeS]** -> CYP
what does the "*" denote |
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Definition
| *This represents the enzyme “NADPH-adrenodoxin reductase” or simply “adrenodoxin reductase”. |
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Term
in NADPH -> [FAD]* -> [FeS]** -> [FeS]** -> CYP
what does the "**" denote |
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Definition
| **This represents adrenodoxin which contains two “iron-sulfur clusters” (also known as nonheme iron centers). |
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Term
| sites of Cytochromes P450 in synthesis of steroid hormones |
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Definition
Adrenal cortex
aldosterone
dehydoepiandrosterone and androstenedione
Testes
Ovaries |
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Term
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Definition
| (cortisol (zona faciculata) |
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Term
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Definition
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Term
| dehydoepiandrosterone and androstenedione |
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Definition
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Term
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Definition
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Term
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Definition
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Term
| Intracellular locations of sites of Cytochromes P450 in synthesis of steroid hormones |
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Definition
| Mitochonrion and endoplasmic reticulum (micorsome) |
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Term
what enzyme is used for this rxn
Cholesterol -> Pregnenolone |
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Definition
Side-chain cleavage enzyme (desmolase); CYP11A1; mitochondrial
3 NADPH and 3 02 used |
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Term
what enzyme is used for this rxn
Pregnenolone -> Progesterone |
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Definition
3B-ol dehydrogenase-5,4-isomerase; cytosolic
aka 3B-hydroxysteroid dehydrogenase |
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Term
where
Progesterone -> 11-Deoxycorticosterone |
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Definition
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Term
where
11-Deoxycorticosterone -> Corticosterone |
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Definition
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Term
where
Corticosterone -> 18-OH-Corticosterone |
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Definition
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Term
where
18-OH-Corticosterone -> Aldosterone |
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Definition
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Term
where
Cholesterol -> Pregnenolone |
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Definition
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Term
where
Pregnenolone -> 17a-OH-Pregnenolone |
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Definition
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Term
where
17a-OH-Progesterone -> 11-Deoxycortisol |
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Definition
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Term
where
11-Deoxycortisol -> Cortisol |
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Definition
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Term
what enzyme is used for this rxn
17a-OH-Pregesterone -> 17a-OH-Progesterone |
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Definition
| 3b-ol dehydrogenase-5,4-isomerase; cytosolic |
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Term
what enzyme is used for this rxn
17a-OH-Pregnenolone -> Dehydroepiandrosterone |
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Definition
| C2 Side-chain cleavage enzyme (C17,20-lyase); identical to 17-Hydroxylase; CYP17; endoplasmic reticulum |
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Term
what enzyme is used for this rxn
17a-OH-Progesterone -> Androstenedione |
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Definition
| C2 Side-chain cleavage enzyme (C17,20-lyase); identical to 17-Hydroxylase; CYP17; endoplasmic reticulum |
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Term
Pathways in gonads:
Androgens: |
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Definition
| Cholesterol -> Pregnenolone -> Progesterone -> 17a-OH-Progesterone -> Androstenedione -> Testosterone |
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Term
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Definition
| Cholesterol -> …-> Testosterone -> 17B-Estradiol |
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Term
what enzyme is used for
Testosterone -> 17B-Estradiol
and where |
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Definition
aromatase
endoplasmic reticulum of the cells in the ovary and the placenta. |
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Term
| NITRIC OXIDE SYNTHASES structure |
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Definition
Cytochrome P450-like monooxygenases
Five prosthetic groups are required-heme, tetrahydrobiopterin, FAD, FMN and NADPH. |
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Term
| NITRIC OXIDE SYNTHASES isoforms |
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Definition
NOS-I (nNOS): nueronal isoform
NOS-II (iNOS): induced or macrophage isoform
NOS-III (eNOS): endothelial isoform |
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Term
| Oxygen atoms incorporated into ______ are derived from |
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Definition
both L-citrulline and NO
atmospheric (molecular) oxygen |
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Term
| Functions of nitric oxide |
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Definition
1.Neurotransmission in brain and peripheral autonomic nervous system
2.Killing of bacteria and tumor cells
3.Vasodilation-important in regulation of blood pressure and penile erection |
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