Metals

bulk eliments trace eliments for some species Periodic Table

Metals essential for life: The role for most is uncertain Na, K, Mg, Ca V, Cr, Mn, Fe Co, Ni, Cu, Zn Mo, W

General roles of metal ions in biology Na, K: Na, K:Charge carriers Osmotic and electrochemical gradients Nerve function Mg, Ca: Mg, Ca:Enzyme activators Structure promoters Lewis acids Mg 2+ : chlorophyll, photosynthesis Ca 2+ : insoluble phosphates

Other metal ions: less well defined and more obscure roles Zn: Zn: Metalloenzymes Structure promoters Lewis acid Not a redox catalyst! Fe, Cu, Mo: Fe, Cu, Mo: Electron-transfer Redox proteins and enzymes Oxygen carrying proteins Nitrogen fixation

Biochemical Reactivity Promotion of Appropriate Geometry Change acid/base character Change Redox potentials Change ionic concentration Formation of Unique species Formation of structural materials Activation of small molecules (NO)

Zinc and Copper Zinc is found in more than 80 different enzymes.  Carboxypeptidase Catalyzes hydrolysis of peptide bonds  Carbonic anhydrase CO 2  HCO 3 - Copper  Ceruloplasmin – blue-glycoprotein Iron storage and oxidation/reduction  Superoxide dismutase Conversion of superoxide to peroxide to water.  Also Lactase, ascorbate oxidase and plastocyanin

Alkali metals Terrestrial distribution: LiNaKRbCsFr nm0.133 nmionic radii nm Distribution in vivo: (Li)NaK(Rb)

Element% of total number of atoms in human body Number of grams in a 70-kg Man H O C N Ca P K S Cl Na Mg Fe < Mn, Co, Cu, Zn, Mo, V, Cr, Ni, F, < Si, Se, As

Role: Na + Extracellular fluid Osmotic balance „sodium pump” Acid-base balance Conformation of proteins nucleic acids Electrical impulse of nerve system Mg 2+ 3Na + ic + 2K + ec + ATP 4- + H 2 O 3Na + ec + 2K + ic + ADP 3- + HPO H +

K+K+ Enzyme activator Conformation of proteins RNA (replication) Secretion of gastric acid Transmembrane potentials! Complexes of alkali metals (Na +, K + ) Cyclic antibiotics Valinomycin Monactin Nonactin polyetherssynthetic cryptands

18-Crown-618-Crown-6 negative charge concentrated in cavity inside the molecule O OO O O O

18-Crown-618-Crown-6 O OO O O O

18-Crown-618-Crown-6 forms stable Lewis acid/Lewis base complex with K + O OO O O O K+K+

18-Crown-618-Crown-6 O OO O O O K+K+

Alkaline Earth Metals Terrestrial distribution: Be MgCaSrBaRa Distribution in vivo: MgCa Be, Ba TOXIC! Sr (not particularly toxic) 90 Sr accumulates in bones

Element% of total number of atoms in human body Number of grams in a 70-kg Man H O C N Ca P K S Cl Na Mg Fe < Mn, Co, Cu, Zn, Mo, V, Cr, Ni, F, < Si, Se, As

Mg 2+ Plants chlorosis CHLOROPHYLL nervous system (tetany) active transport (intracellular) enzyme activator (e.g. ATP-ase) Ca 2+ antagonist Ca 2+ Inhibits Mg 2+- activated enzymes Extracellular: clotting (10 -3 M) Ca 2+ prothrombin thrombin-fibrinogen-fibrin Alkaline Earth Metals

Chlorophyll

The interactions between ATP, Mg 2+, and arginine and lysine residues at the active site of an enzyme Since all the negative charges in ATP are neutralized, ATP is readily approached by nucleophiles

- plasma proteins bones (hydroxyapatite) Ca 5 (PO 4 ) 3 (OH) - intracellular: enzymes mol/dm 3 - muscle contraction: troponin - Calcium triggering: calmodulins (Ca-binding proteins) largely helical and undergo helix/helix motion Ca-binding hands: a short two-strand unit  -sheet

Ca 2+ signal metabolic controls N T P Protein phosphatasec-NMP protein DNA New signals