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18 Cards in this Set
- Front
- Back
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What are the Zn cellular transporters?
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Two classes of Zn cellular transporters:
ZIP: moves zinc into cell AND/or organelle ZnT: efflux |
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How is Zn transported in plasma?
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Instestine->liver: bound to albumin
In plasma: 2/3 bound to albumin ("available") and 1/3 bound to a-2-macroglobulin |
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What can drop the amount of Zn•albumin complex in plasma?
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1. Deficiency (but must be severe)
2. Trauma, bact. infection, inflamation - acute phase response causes redistribution of Zn in body |
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How is Zn homeostasis maintained?
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Through absorption/excretion, but not well defined.
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How is Zn lost?
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Through feces: many enzymes lost in sloughed intestinal cells, some Zn is lost w/bile, also pancreated secretions w/Zn-containing enzymes
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What is Zn's biochemical role?
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Zn is found in 200+ "metalloenzymes" - sometimes a structural or regulatory role, but often times site of subtrate binding
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Why don't we use a functional test for Zn?
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Many Zn enzymes have EXTREMELY high affinity for Zn. Zn plasma is used, but it's not a very good measure.
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What are some examples of enzymes w/Zinc?
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Alchohol dehydrogenase
Nucleotide polymerase -DNA/RNA production Alkaline phosphatase Aminopeptidase - protein met Carboxypeptidase Collagenase Carbonate anhydrase - acid/base regulation d-aminolevulinate hydratase - heme synthesis |
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What are Zn fingers?
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Zn fingers are unique structures of certain proteins - they contain Zn, which is bound to 2 Cys's and two Hys AA's of protein; one hydrophilic AA at fingertip.
Zn fingers wrap around DNA and lie in major grove. The affect rate of translation of certain genes. |
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What categories of proteins have zinc fingers?
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• Transcription factors
• Transcription/Replication enzymes • DNA repair enzymes • Apoptosis enzymes (p53) |
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How is Zn involved in DNA repair?
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Enzymes involved in DNA repair including many in the BER/NER require Zn. Also, poly (ADP-ribose) polymerase
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What are some transcription/replication enzymes that contain Zn?
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• Replication Protein A
• Deoxynucleotide terminal transferase |
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What are the signs of Zn deficiency => ACUTE
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anoerexia, change in taste, smell; keratanization of the eyes; depression, lethargy; dermatitis, alopecia
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What are the signs of Zn deficiency => CHRONIC
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Growth retardation, delayed sexual development (hypogonadal dwarfism). Complications of pregnancy (birth defects).
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What causes deficiency?
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Inborn error of absorption
"AE" acrodermatitis enteropathica or Poor diet, diet low in Zn (Fe), malabsorption, increased losses (trauma- burns) |
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What are the signs of acrodermatitis enteropathica?
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Appears in first few weeks of life: severe dermatitis, diarrhea, alopecia
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What is the cause of acrodermatitis enteropathica?
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Inborn error of absorption: mutation in ZIP4 gene prevents proper absorption
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How is AE treated?
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High doses of Zn 3x daily
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