Trace Elements Flashcards by Kyra Catedral

• Usually associated with an enzyme (metalloenzyme) or another protein (metalloprotein) as an essential component or cofactor

TRACE ELEMENTS

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• Deficiencies typically impair one or more biochemical functions

• Excess concentrations are associated with at least some degree of toxicity

TRACE ELEMENTS

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is the most commonly used for determinations

AAS

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METHODS AND INSTRUMENTATION

• AAS

• FAAS

• AES

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Chromium
Cobalt
Copper
Fluorine lodine
Tron
Manganese
Molybdenum
Selenium
Zinc

Essential in humans and animals

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Essential in humans and animals

Chromium
Cobalt
Copper
Fluorine lodine
Tron
Manganese
Molybdenum
Selenium
Zinc

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Not essential

Aluminum
Antimony
Bismuth
Germanium
Mercury
Silver
Thallium
Titanium

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Aluminum
Antimony
Bismuth
Germanium
Mercury
Silver
Thallium
Titanium

Not essential

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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

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Iron is

Stored as____ and _____

– Bone marrow, spleen, and liver

ferritin and hemosiderin

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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

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facilitates diffusion of oxygen into tissue because it binds oxygen with greater affinity than hemoglobin

Myoglobin

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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

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(2) are iron-containing enzymes that convert H2O2 to water

Peroxidase and catalase

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– pregnant women, both young children and adolescents, and women of reproductive age

– Increased Blood Loss

– Decreased iron intake

– Decreased release from ferritin

IDA

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– genetic defect that causes tissue accumulation of iron, affects liver function, and often leads to hyperpigmentation of the skin

Genetic/Hereditary Hemochromatosis

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– increased serum iron and TIBC or transferrin, but without demonstrable tissue damage

HEMOSIDEROSIS

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increases in iron deficiency and decreases in iron overload

Serum Transferrin Receptors

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• 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