Chemistry of metal ions in biology: metalloproteins, iron–sulfur clusters, heme, metallocofactors. The interface of coordination chemistry and biochemistry; substrate of enzymology of hydrolases, oxidoreductases, and photosynthesis.
bioinorganic-chemistry
Metalloprotein
Protein containing one or more metal-ion cofactors coordinated by donor atoms (His-N, Cys-S, Asp/Glu-O, backbone). Approximately one-third…
Heme cofactor
Porphyrin-Fe(II/III) prosthetic group in hemoglobin, myoglobin, cytochromes, peroxidases. Axial ligand geometry (5-coordinate vs…
Iron–sulfur cluster
[Fe_nS_n] redox cofactors (n=2,3,4) bound by Cys. Electron-transfer workhorses of respiration and photosynthesis (ferredoxin, complex I/II,…
Zinc finger motif
Small (~30-residue) DNA/protein-binding fold stabilised by tetrahedral Zn²⁺ coordination, typically Cys₂His₂. Zn is non-redox-active but a…
Cytochrome P450
Heme-thiolate monooxygenases that activate O₂ for hydroxylation of unreactive C–H bonds via compound-I (Fe(IV)=O porphyrin radical cation).…
Photosystem II oxygen-evolving complex
Mn₄CaO₅ cluster that accumulates four oxidising equivalents via Kok S-state cycle (S₀→S₁→S₂→S₃→S₄→S₀) to couple 2 H₂O → O₂ + 4 H⁺ + 4 e⁻.…
Nitrogenase (FeMo-co)
Mo–Fe₇–S₉–C cluster that reduces N₂ to 2 NH₃ under ambient conditions (vs ~450°C/200 atm industrial Haber–Bosch). ATP-driven electron…
Chelation therapy
Multidentate ligands (EDTA, DMSA, deferoxamine) sequester toxic metal ions (Pb, As, Fe-overload) via thermodynamically stable complexes…
Coordination geometry of metal-binding sites
Metalloprotein active-sites adopt characteristic coordination geometries: tetrahedral (Zn-fingers), square-planar (heme), octahedral…
Spin-state crossover in metalloproteins
Heme-iron, cytochrome-P450 reaction-cycles involve Fe(II/III) HS↔LS transitions modulated by axial ligand-field strength. Tanabe-Sugano…
Magnesium-RNA folding
Mg²⁺ ions stabilise RNA-tertiary-structure via direct + diffuse counter-ion binding to phosphate-backbone. Hill-coefficient cooperative…
Metal-binding site prediction (computational)
Bertini-Rosato 2008 / Babor-Pieper 2008: sequence + structure features (CHED triad cysteine-histidine-glutamate-aspartate frequency,…
Crystal field theory (Bethe 1929)
Bethe 1929 + Van Vleck 1932: octahedral d-orbital splitting Delta_o between t2g + eg; high-spin vs low-spin governed by Delta_o vs P…
Hemoglobin cooperativity (Perutz)
Perutz 1963 (Nobel 1962) Hb 4 subunits T<->R quaternary transition; Hill coefficient n=2.8; Bohr effect H+/CO2 pK_R<pK_T allosteric…
Nitrogenase Fe-Mo-co (Rees-Howard 1992)
Rees-Howard 1992 X-ray Mo7Fe-cluster + interstitial-C 2002: 8e- 8H+ N2 + 16ATP -> 2NH3 + H2; 100 atm at ambient T; biological alternative…
Vitamin B12 / cobalamin (Hodgkin)
Hodgkin 1956 (Nobel 1964) B12 X-ray structure: corrin ring + Co3+ + 5,6-dimethyl-benzimidazole; methylcobalamin + adenosylcobalamin…
Zinc finger (Klug 1985 TFIIIA)
Klug 1985 (Nobel 1982 EM-related) zinc-finger Cys2His2 fold; ~30 aa coordinates Zn2+; foundation of sequence-specific DNA recognition +…
Photosystem II Mn4Ca cluster (Umena 2011)
Umena-Kawakami-Shen-Kamiya 2011: 1.9 A X-ray of PSII Mn4CaO5 cluster; 4 photons drive S0->S4 Kok cycle; H2O -> O2 + 4H+ + 4e-; basis of…
Hemoglobin (Perutz 1968)
M Perutz 1962 (Nobel 1962) Hb-structure + 1968 cooperativity-T-R; modern allostery + Bohr-effect + 2,3-BPG modulation.
Z-scheme (Hill 1937)
R Hill 1937 + Calvin Nobel 1961 photosystem-Z-scheme; modern PSII Mn4O5Ca cluster + Fenton + radical oxygen mechanism.
Nitrogenase (Burns 1965)
R Burns 1965 + Howard 1996 FeMo-cofactor; modern Hu-Ribbe 2014 V-nitrogenase + Spatzal 2014 carbide center.
Cytochrome (Warburg 1925)
O Warburg 1925 (Nobel 1931) cytochrome-oxidase respiration; modern complex-IV proton-pumping + crystal-Yoshikawa 1996.
Ferritin (Laufberger 1937)
V Laufberger 1937 ferritin-iron-storage; modern 24-subunit cage + 4500 Fe + nanocage drug-delivery + magnetic-imaging.
Zn finger (Klug 1985)
A Klug 1985 (Nobel 1982) zinc-finger TFIIIA; modern ZF-TF designer + ZFN gene-editing + 2024 Cas-fusion ZF-replacement.