Zn,Cu,Mg Flashcards
What are the key characteristics of Zn, Cu, and Mn?
Physiological activity, absorption, storage, transport mechanisms, dietary sources, and recommended intakes
What defines transition elements?
Have d or f subshells that allow them to transfer between different oxidation states
Is Zinc (Zn²⁺) a true transition metal?
No, but it shares similar properties
What are metalloenzymes?
Complexes where a metal ion (Zn, Cu, Mn) acts as a cofactor in enzyme activity
What key role do metals play in enzyme activity?
Act as Lewis acids, forming stable complexes with enzymes
Provide an example of a metalloenzyme involving Zn²⁺.
Zn²⁺ binds to Carboxypeptidase, forming an active metalloenzyme
What are the general biological roles of metalloenzymes?
- Signaling
- Structural
- Catalytic
- Regulatory
What is a significant properties of Zinc in terms of its placement in the body and function?
-One of the most abundant intracellular ions, after K⁺ and Mg²⁺
-found in every compartment / organelle
-very strong lewis acid
-only functions in the Zn2+ state
What is the valence state of Zinc?
Zn²⁺
How does the valence state of Zn2+ differ from other metalloenzymes? provide specific examples.
Mn and Cu can function in different valence states for redox reactions
What is the role of Superoxide Dismutase (SOD) related to Zinc? what are the different forms of SOD? how does the activity of SOD change with deficiencies? what metals are expected to change the activity if deficient?
Detoxifies superoxide radicals (O₂⁻) to prevent oxidative damage
Cu/Zn-SOD: intracellular/extracellular
Mn-SOD: associated with mitochondria
reduced activity of SOD with Cu/Zn or Mn is deficient
What are zinc finger motifs?
Protein structures where Zn²⁺ binds to amino acids, stabilizing DNA-protein interactions
-formation of a loop/finger to stabilize protein
Why does copper deficiency lead to iron accumulation?
Ferroxidases require copper for function.
Without copper, ceruloplasmin and hephaestin lose their activity, preventing Fe²⁺ from converting to Fe³⁺.
-Iron gets trapped in cells, leading to anemia and iron buildup.
what is ferroxidase? What is the relationship between ferroxidase activity and ceruloplasmin?
an enzyme that catalyzes oxidation of Fe2+ to Fe3+
-Ceruloplasmin is the major plasma ferroxidase
What is the effect of Zinc deficiency on immune function? how is Cu involved in immune function?
Leads to thymulin hormone reduction, causing thymus shrinkage and impaired T-lymphocyte production
-Cu maintains neutrophils and granulocytes and the maturation of early stem cells
What oxidation states can Copper function in?
Cu¹⁺ and Cu²⁺
What is Ceruloplasmin?
1) Major copper-binding protein in plasma, oxidizes Fe²⁺ → Fe³⁺
2) Involved in Cu transport around the body
What is the role of lysyl oxidase? what metal is also involved?
Cu is involved in bone mineralization by providing the collagen matrix via lysyl oxidase
-Cu needed as a cofactor for the lysyl oxidase enzyme
What is the role of Manganese in Superoxide Dismutase (SOD)?
Mn-SOD is critical for mitochondrial antioxidant defense
How is manganese associated with cartilgage formation? What is the effect of Manganese deficiency?
It is required to make larger sugar molecules (glycosaminoglycan), which is needed to make the network of glycoproteins that make up cartilage
Deficiency results in skeletal and growth abnormalities, including ear bone defects
Where does absorption of Zn, Cu, and Mn occur? how is it absorped? what is the efficiency of this? what would you expect of absorption based off diet?
In the small intestine
-Carrier mediated and passive transport provides low efficiency of absorption
-typically linear in relation to diet
What is Metallothionein (MT)? how does it do this?
Intracellular protein that binds Zn, Cu, and heavy metals, reducing metal absorption
-binding of metals increases storage of them within the cell, once epithelial cells are sloughed off, this allows the metals to be excreted with it
List factors that enhance the absorption of Zinc and Copper.
- Low dietary intake
- Gastric acid
- Organic acids (citrate)
List factors that inhibit the absorption of Zinc and Copper.
- High phytate (grains, legumes)
- High calcium intake
- Fiber (non-fermentable)
