Zn, Cu, Mn Flashcards
This group is usually defined as transition elements, though which one is not?
Zinc, but has the same properties
The equation to get a metalo-complex
Lewis acid (metal ion) + Lewis base (Ligand - AA/H20) –> MLC
Four general biological roles of metalloenzymes
signaling
structural
catalytic
regulatory
Properties of Zn
Most common ions within the cell (except K+, Mg2+)
Found in every compartment and organelle
Very strong Lewis Acid
One valence state = limited in fxn (2+)
What is Zn main role in cytosolic and extracellular SOD
Structural role / folding of the proteins
How many AA are required for the zinc finer region or motif
4 AA residues
What role do zinc fingers play in gene transcription
folding pattern of a sequence of AA around a loop to stabilize DNA sequence
It has been proposed Zn deficiencies can lead to stunted growth in children, why?
IGF-1 receptor is activated by a promoter region that contains a zinc finger DNA binding region
Why would Zinc and Copper impair immunity
Zinc (lymphocytes) - maintenance of B & T cells, deficiency can cause decreased thymulin hormones and smaller size thymus (Tcells)
Cu (leukocytes) - regulate neutrophils and granulocytes, maturation of early stem cells, regulates T cell proliferations through IL-2
We need ___ for the mobilization of iron
Copper
What is the importance of Ceruloplasmin?
Secreted by the liver in response to Cu conc
Involved in transport of 90% of copper around the body
Responsible for oxidation of Fe2 to Fe3+
What role does copper play in bone mineralization?
Providing the collagen matrix through lysyl oxidase - linkage enzyme provided to collagen and elastin
Cardiac dysfunction due to copper would be from?
deficiency of lysyl oxidase to elastin
What is the first step in SOD to remove superoxide
1st step is to change superoxide to hydrogen peroxide
Where are the different forms of SOD found?
Cu/Zn: intracellular and extracellular fluids
Mn-SOD: Mitochondria
When would reduce SOD activity occur?
deficiency (Zn,Mn,Cu), causing:
- increased lipid peroxidation
- oxidative stress
- reduced energy regulation in mito
What part does Mn play in cartilage formation
Syn of glycosaminoglycan - elongation of sulphate chains
Where are all 3 element absorbed and how effective is absorption?
Small I
Relatively low - linear related to amount in diet
Define intestinal absorption kinetics in terms in saturable and diffusional
Diffusional: defined by linear relationship b/w mineral content and amount absorbed
Saturable: varies dependent upon the mineral content of the intestine (@ low mineral content it is effect, and at high it’s low)
In what 2 ways is zinc transported into the intestinal epithelium?
Transcellular transport (ZIP4) + ZnT5B - Brush boarder
Inside the cell Zinc and Cu both bind ___? what is the downside to this?
Metallothionein
If one element is too high within the diet, Metallothionein will bind both and cause an unwanted down regulation
Metallothionein: properties and role
Low molecular weight protein
Produced to response to high levels of Zn, Cu, Cadmium and mercury
Role: Bind and maybe store metals within the cell
- Block or reduce uptake
Enterocytes can accumulate MT-bound metals. How are they removed?
Sloughed off from the mucosa and excreted usually in feces
When in ZIP4 upregulated?
During low Zn status
