Trace Elements Flashcards
• Usually associated with an enzyme (metalloenzyme) or another protein (metalloprotein) as an essential component or cofactor
TRACE ELEMENTS
• Deficiencies typically impair one or more biochemical functions
• Excess concentrations are associated with at least some degree of toxicity
TRACE ELEMENTS
is the most commonly used for determinations
AAS
METHODS AND INSTRUMENTATION
• AAS
• FAAS
• AES
Chromium
Cobalt
Copper
Fluorine lodine
Tron
Manganese
Molybdenum
Selenium
Zinc
Essential in humans and animals
Essential in humans and animals
Chromium
Cobalt
Copper
Fluorine lodine
Tron
Manganese
Molybdenum
Selenium
Zinc
Not essential
Aluminum
Antimony
Bismuth
Germanium
Mercury
Silver
Thallium
Titanium
Aluminum
Antimony
Bismuth
Germanium
Mercury
Silver
Thallium
Titanium
Not essential
IRON
• ___grams
–_____ g of iron is in hemoglobin (red blood cells)
– 130 mg in myoglobin
– 8 mg bound to enzymes
– 3 – 5 mg is found in plasma associated with transferrin, albumin, and free hemoglobin
3 – 5
2 – 2.5
Iron is
Stored as____ and _____
– Bone marrow, spleen, and liver
ferritin and hemosiderin
Dietary Requirements
– In adult male, the average loss of 1 mg ____ per day must be replaced by dietary sources
– Pregnant or premenopausal women and children have greater ___ requirements
IRON
facilitates diffusion of oxygen into tissue because it binds oxygen with greater affinity than hemoglobin
Myoglobin
are essential for electron transport in the respiratory chain, with reversible cycling of ferric iron to ferrous iron, resulting in the production of ATP
Cytochromes
(2) are iron-containing enzymes that convert H2O2 to water
Peroxidase and catalase
– pregnant women, both young children and adolescents, and women of reproductive age
– Increased Blood Loss
– Decreased iron intake
– Decreased release from ferritin
IDA
– genetic defect that causes tissue accumulation of iron, affects liver function, and often leads to hyperpigmentation of the skin
Genetic/Hereditary Hemochromatosis
– increased serum iron and TIBC or transferrin, but without demonstrable tissue damage
HEMOSIDEROSIS
increases in iron deficiency and decreases in iron overload
Serum Transferrin Receptors
• Ferric iron bound to transferrin
• Serum or heparinized plasma
Total Iron Content (Serum Iron)
TIC collection
• Early morning is preferred because of the diurnal variation
• Amount of iron that could be bound by saturating transferrin and other minor iron-binding proteins present in the serum or plasma sample
Total Iron-Binding Capacity (TIBC)
– Is the ratio of serum iron to TIBC
transferrin saturation
– Measured by immunochemical methods (e.g. nephelometry)
• Increased in iron deficiency and decrease in iron overload and hemochromatosis
• May also be decreased in chronic infection and malignancies
– Primarily monitored as an indicator of nutritional status
– Negative acute phase protein, it will decrease in inflammatory conditions
Transferrin
– Measured in serum by immunochemical methods (e.g. ELISA)
– Decreased in iron deficiency anemia
– Increased in iron overload and hemochromatosis
– Often increased in several other conditions
Ferritin
COPPER
• Dietary Requirements
– Shellfish, liver, nuts, and legumes
Absorption, Transport, and Excretion
– – regulation of copper
Intestines
Copper becomes bound to albumin or complexed to histidine residues as it is transported to the liver where it is stored in the form of..
cuproproteins
Copper
– Small amount bound to albumin and_____
– Mostly incorporated into____
transcuperin
ceruloplasmin
– Synthesized in the liver and has ferroxidase activity, converting ferrous iron to ferric iron as it is incorporated into transferrin
– Acute phase protein
Ceruloplasmin
Copper
• Mainly removed by_____ excretion as unabsorbed dietary copper and contained in biliary and intestinal secretions
• Less than____% is lost in urine and sweat
fecal
3
Component of enzymes involved in redox reactions, with many involving reactions with oxygen
– Ceruloplasmin
– Cytochrome c oxidase
– Superoxide dismutase
– Dopamine-beta-hydroxylase
– Tyrosinase
– Ascorbate oxidase
Copper
competes with copper for absorption from the intestine
– Increase ___ intake could cause copper deficiency
Zinc
– recessive X-linked genetic defect in copper transport and storage
Menkes’ syndrome
– hepatolenticular degeneration
– Associated with copper accumulation in the liver, brain, kidney, and cornea (KayserFleischer ring)
Wilson’s disease
Richest source of zinc
– Meat, fish, and dairy products
Zinc
Absorption, Transport, and Excretion
– Mainly absorbed in the_____
–_____% = transported in the circulation by albumin
–_____% = alpha2-macroglobulin
– Major route of excretion is by the feces and 25% is by_____
– Relatively small amount in urine and sweat
small intestine
65
35
pancreatic secretion
Biochemical Functions
– Metal cofactor for enzyme activity
– Usually an integral component of the active site of the enzyme
• ALP, Alcohol dehydrogenase, carbonic anhydrase, DNA and RNA polymerases
Zinc
– For growth
wound healing
integrity of connective tissues
reproductive function
immune system
protection from free radical damage
Zinc
Symptoms:
• Growth retardation
• Dwarfism
• Sensory alterations
• Susceptibility to infection
Deficiency in zinc
COBALT
• Constituent of vitamin____, which is involved in folate metabolism and erythropoiesis
B12
• May be absorbed by the same metabolism as iron
• Has toxic effects at high doses
• AAS for measurement
Cobalt
• Use in metal alloys, metal plating, dyes, and leather tanning
• Natural or industrial waste
CHROMIUM
• +6 ion is far more toxic than the +3 ion
• Richest source is diet
• Transported to the tissue by transferrin
• Important in glucose metabolism as an essential activator of insulin
CHROMIUM
• Preventing dental caries
• Excess is associated with mottling of teeth and calcification in soft tissue
• May also minimize bone loss or even stimulate bone formation
• Readily absorbed by the gut and distributed totally to the bone and teeth
FLUORIDE
• Largely protein-bound
• Activator of several enzymes
• Transported in plasma by albumin, alpha2macroglobulin, and transferrin
• Excreted in bile and pancreatic secretions
MANGANESE
• Cofactors for several oxidase enzymes
• Mostly absorbed in the stomach and small intestine
• Released and excreted either in the urine or in the bile
• Excess exposure may cause inhibition of copper-dependent enzymes (ceruloplasmin and cytochrome oxidase)
MOLYBDENUM
• Cofactor in glutathione peroxidase and iodothyronine diodinase
• Antioxidant properties and is involved in metabolism of thyroid hormones
• Deficiency found in: cardiomyopathy and skeletal weakness, osteoarthritis, and increased incidence of cancer
SELENIUM
