Sulfur atoms in bioorganic molecules (thiols, thioesters, disulfides)

What is the structure of thiols?

Thiols have the structure –SH, with a sulfur atom bonded to a hydrogen atom. Example: Cysteine.

What role do thiols play in proteins?

Thiols in cysteine residues form disulfide bonds (–S–S–), stabilising protein structure and aiding in proper folding.

How do thiols participate in redox reactions?

Thiols can be oxidised to form disulfide bonds, and disulfide bonds can be reduced back into thiols.

What is the general structure of thioesters?

Thioesters have the structure R–C(=O)–S–R', where sulfur replaces oxygen in esters. Example: Acetyl-CoA.

Why are thioesters important in metabolism?

Thioesters like Acetyl-CoA participate in the transfer of acyl groups in metabolic pathways, including the Krebs cycle.

Why are thioesters more reactive than esters?

The weaker bond between carbon and sulfur makes thioesters more reactive, allowing easier acyl group transfer.

What is the structure of disulfides?

Disulfides have the structure –S–S–, formed by the oxidation of two thiol groups from cysteine residues.

What role do disulfide bonds play in proteins?

Disulfide bonds help stabilise tertiary and quaternary protein structures, especially in extracellular proteins.

How can disulfide bonds be broken?

Disulfide bonds are broken by reducing agents, converting them back into thiol groups.

What is the significance of sulfur in redox reactions?

Sulfur-containing molecules help maintain cellular redox balance and protect cells from oxidative stress.