Metals in Biology

Found in:Extracellular fluid, blood plasma, nerves

Nerve impulse transmission, fluid balance, maintains membrane potential via Na⁺/K⁺-ATPase pump

KPotassiumZ=19

Found in:Intracellular fluid, muscle cells, neurons

Nerve impulse transmission, muscle contraction, intracellular osmotic balance

CaCalciumZ=20

Found in:Bones, teeth, blood, intracellular stores

Bone and teeth structure (hydroxyapatite), muscle contraction, blood clotting, signal transduction

MgMagnesiumZ=12

Found in:Bones, muscle, chloroplasts, all cells

Central atom in chlorophyll, cofactor for >300 enzymes including ATP-dependent reactions

Essential Trace Metals

Required in small amounts; critical cofactors for enzymes and proteins

FeIronZ=26

Found in:Red blood cells, liver, spleen, mitochondria

Oxygen transport in hemoglobin, electron transfer in cytochromes and iron-sulfur clusters

ZnZincZ=30

Found in:All tissues, prostate, retina, pancreas

Enzyme catalysis (carbonic anhydrase, carboxypeptidase), zinc finger transcription factors, immune function

CuCopperZ=29

Found in:Liver, brain, kidneys, mitochondria

Electron transport (cytochrome c oxidase), connective tissue crosslinking (lysyl oxidase), antioxidant (SOD)

MnManganeseZ=25

Found in:Mitochondria, bones, chloroplasts

Photosynthetic water oxidation (OEC), antioxidant defense (MnSOD), bone formation

CoCobaltZ=27

Found in:Liver, kidneys, bound in vitamin B₁₂

Core of vitamin B₁₂ (cobalamin), essential for red blood cell formation and DNA synthesis

MoMolybdenumZ=42

Found in:Liver, kidneys, legume root nodules

Nitrogenase cofactor (biological nitrogen fixation), xanthine oxidase, sulfite oxidase

SeSeleniumZ=34

Found in:Thyroid, liver, kidneys, all tissues

Selenocysteine in glutathione peroxidase (antioxidant), thyroid hormone metabolism (deiodinases)

CrChromiumZ=24

Found in:Liver, spleen, soft tissue

May enhance insulin signaling and glucose metabolism (debated essentiality)

Therapeutic Metals

Used in medicine as drugs, diagnostic agents, or treatments — Learn more →

LiLithiumZ=3

Therapeutic use

Mood stabilizer for bipolar disorder; modulates inositol signaling and GSK-3β

Found in:Administered as lithium carbonate; distributes in CNS

PtPlatinumZ=78

No biological role

Cisplatin and derivatives for cancer chemotherapy; crosslinks DNA to inhibit replication

Found in:Administered intravenously; accumulates in tumors

GdGadoliniumZ=64

No biological role

MRI contrast agent (gadolinium-DTPA); paramagnetic properties enhance T1-weighted imaging

Found in:Administered intravenously; excreted renally

BaBariumZ=56

Found in:Administered orally; passes through GI tract

Barium sulfate for GI tract imaging (barium swallow/meal); radiopaque contrast agent

TcTechnetiumZ=43

No biological role

Technetium-99m for nuclear medicine imaging (SPECT); gamma emitter with 6-hour half-life

Found in:Administered intravenously; concentrates in target organs

Toxic Metals

Harmful to biological systems; often mimic essential metals or inhibit enzymes — Learn more →

PbLeadZ=82

Found in:Accumulates in bones, brain, kidneys

Neurotoxin; inhibits δ-aminolevulinic acid dehydratase (heme synthesis), mimics Ca²⁺

HgMercuryZ=80

Found in:Accumulates in brain, kidneys, liver

Neurotoxin; methylmercury bioaccumulates in food chains, binds sulfhydryl groups in enzymes

CdCadmiumZ=48

Found in:Accumulates in kidneys, liver, bones

Kidney damage (proximal tubule); displaces Zn in metallothionein, disrupts calcium metabolism

AsArsenicZ=33

Found in:Accumulates in hair, nails, skin, liver

Inhibits pyruvate dehydrogenase and other enzymes by binding dithiol groups; disrupts ATP production

TlThalliumZ=81