Lecture 15_2025

Biological Inorganic Chemistry Overview

• Biological Inorganic Chemistry (Bio-inorganic Chemistry) is an interdisciplinary field bridging inorganic chemistry, biology, and biochemistry.

• Major focus is on the role of metallic and non-metallic elements in biological systems.

• Key research areas include:

  • Inorganic elements in nutrition and toxicity remedies in natural and human systems.

  • Metal complexes as probes and drugs.

  • Biomineralization: the creation of minerals by living organisms to harden biological tissues.

Essential Elements in Bioinorganic Chemistry

• Elements such as carbon (C), hydrogen (H), nitrogen (N), oxygen (O), phosphorus (P), and sulfur (S) form the foundation of cellular components (proteins, nucleic acids, lipids, etc.).

• Essential trace metals (e.g., iron, zinc) are vital for biological processes.

• Life has adapted to utilize Earth’s minerals and ions, showcasing the ability to use inorganic elements for critical functions.

Periodic Table and Biological Importance of Metals

• The periodic table is divided into bulk essential elements and trace essential elements:

  • Bulk: e.g., calcium (Ca), sodium (Na), potassium (K)

  • Trace: e.g., iron (Fe), zinc (Zn), copper (Cu)

• Most biological metals correlate with earth-abundant elements, though bioavailability varies greatly across environments.

Sequestration of Metals

• Sequestration refers to the acquisition and transport of metal ions into cells.

• Iron sequestration is crucial for life, often achieved through siderophores that bind iron efficiently in biological systems.

• The oxidation state of iron varies with pH, influencing its bioavailability.

Binding Mechanisms in Metal Transport

• Biologically significant metals, like iron, often exist as insoluble minerals, necessitating effective binding ligands for transport.

• EDTA4- is a synthetic ligand with high affinity for Fe2+ and Fe3+, aiding in metal binding and transport within systems.

Metalloproteins: Structure and Function

• Transition metals in metalloproteins serve as catalytic active sites, contributing to enzymatic activity due to their versatility in coordination and oxidation states.

• Notable metalloproteins include ferritin (iron storage) and calmodulin (calcium binding) facilitating biological signaling and structural integrity.

Iron Storage: Ferritin

• Ferritin acts as an iron storage molecule, accommodating about 4500 iron atoms in its structure.

• It consists of an organic coating that maintains solubility and regulates iron core growth, optimizing iron mobilization under varying conditions.

Calcium and Sodium in Cellular Function

• Sodium and calcium ions predominantly exist extracellularly while potassium and magnesium are found intracellularly.

• Metal ions like calcium act as signaling molecules, inducing conformational changes in proteins that trigger physiological responses (e.g., neurotransmission).

Zinc Fingers: Structural Proteins

• Zinc ions in zinc fingers serve primarily structural roles in transcription factors, helping proteins maintain appropriate shapes for DNA interaction.

• The exact regulatory role of zinc concentrations in gene expression remains uncertain.

Chemistry of Hemes and Oxygen Transport

• Heme is an iron-containing molecule critical for oxygen transport in hemoglobin, with a porphyrin structure.

• Hemoglobin binds O2 reversibly; its conformation changes with oxygen concentration, facilitating oxygen delivery in tissues.

Vitamin B12: Cobalt's Role in Biology

• Vitamin B12 (cobalamin) is essential for DNA synthesis and neurological function, with cobalt at its core.

• Deficiencies lead to conditions such as pernicious anemia, emphasizing its importance in human health and metabolic processes.

Transferrin: Iron Transport Mechanism

• Transferrin binds and transports iron in the body, playing a key role in delivering the necessary iron for red blood cell production.

• Its structure includes binding sites for iron, highlighting the necessity of maintaining iron homeostasis.

Medicinal Applications of Metals

• Metals have therapeutic uses ranging from treating deficiencies to potential adverse effects when they accumulate excessively.

• Gold compounds for rheumatoid arthritis and platinum-based drugs for cancer provide examples of how metals are integrated into medicine.

Biomineralization Process

• Biomineralization is the natural process of mineral formation in organisms (e.g., bones, shells).

• This process is crucial for structural integrity and involves a complex interplay between inorganic and organic components.

Magnetotactic Bacteria and Their Applications

• Magnetotactic bacteria orient themselves using intracellular magnetic particles they create, aiding their movement toward anaerobic conditions.

• Further exploration of these microbes may yield novel materials for technological applications.