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18 Cards in this Set

  • Front
  • Back
What are the Zn cellular transporters?
Two classes of Zn cellular transporters:

ZIP: moves zinc into cell AND/or organelle

ZnT: efflux
How is Zn transported in plasma?
Instestine->liver: bound to albumin

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