What is Cysteine?

Cysteine is one of two sulfur-containing amino acids; the added is methionine. Cysteine differs from serine in a individual atom-- the sulfur of the thiol replaces the oxygen of the alcohol. The amino acids are, however, abundant added altered in their concrete and actinic backdrop than their affinity ability suggest.

Consider, for example, the differences amid H2O and H2S. The hydrogen bonding ability of baptize is able-bodied accepted and is amenable for abounding of its arresting features. Under agnate altitude of temperature and pressure, however, H2S is a gas as a aftereffect of its anemic H-bonding propensity. Furthermore, the proton of the thiol of cysteine is abundant added acid than the hydroxylic proton of serine, authoritative the nucleophilic thiol(ate) abundant added acknowledging than the hydroxyl of serine.

Cysteine aswell plays a key role in stabilizing extracellular proteins. Cysteine can acknowledge with itself to anatomy an breakable dimer by accumulation of a disulfide bond. The ambiance aural a corpuscle is too acerb abbreviation for disulfides to form, but in the extracellular environment, disulfides can anatomy and play a key role in stabilizing abounding such proteins, such as the digestive enzymes of the baby intestine.

Cysteine and methionine are the alone sulfur-containing amino acids.