Changes

==What are Methionine and Cysteine?==

==What are Methionine and Cysteine?==

Methionine and cysteine are '''sulphur containing amino acids'''. '''Cysteine is synthesized endogenously from methionine''', and production of cysteine accounts for approximately half of the methionine requirement in the diet<ref name="Teeter">Teeter RG, et al. Methionine and cystine requirements of the cat. J Nutr 1978;108:291–295</ref>. In this pathway methionine is converted to homocysteine, which in turn donates a sulphur group to serine (a non-essential amino acid) to ultimately form cysteine. Although methionine, but not cysteine, is considered an essential amino acid, the addition of dietary cysteine “spares” and reduces the metabolic requirement for methionine.  

Methionine and cysteine are '''sulphur containing [[Amino Acids Overview - Nutrition|amino acids]]'''. '''Cysteine is synthesized endogenously from methionine''', and production of cysteine accounts for approximately half of the methionine requirement in the diet<ref name="Teeter">Teeter RG, et al. Methionine and cystine requirements of the cat. J Nutr 1978;108:291–295</ref>. In this pathway methionine is converted to homocysteine, which in turn donates a sulphur group to serine (a non-essential amino acid) to ultimately form cysteine. Although methionine, but not cysteine, is considered an essential amino acid, the addition of dietary cysteine “spares” and reduces the metabolic requirement for methionine.  

'''Methionine is a neutral amino acid''', while '''cysteine is basic'''; both methionine and cysteine are '''gluconeogenic'''. Cysteine readily reacts with itself and other thiols (i.e. sulphur containing compounds) and cystine is formed from a disulphide bond between two cysteine molecules. Most of the plasma cysteine is actually found as cystine.

'''Methionine is a neutral amino acid''', while '''cysteine is basic'''; both methionine and cysteine are '''gluconeogenic'''. Cysteine readily reacts with itself and other thiols (i.e. sulphur containing compounds) and cystine is formed from a disulphide bond between two cysteine molecules. Most of the plasma cysteine is actually found as cystine.