Homocysteine

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Homocysteine is an uncommon amino acid. The molecular formula is HOO=CCH(NH2)(CH2)2SH.

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Catabolism

Homocysteine is produced by the hydrolysis of the common amino acid methionine.

Methionine + Water → Homocysteine + Methanol

Homocysteine can also be produced by the hydrolysis of S-adenosyl-L-homocysteine.

S-adenosyl-L-homocysteine + water → adenosine + homocysteine

This reaction is catalyzed by the enzyme S-adenosyl-L-homocysteine hydrolase. [1] This enzyme is involved in normal T-cell and macrophage function[2]

Atherosclerosis

Elevated levels of serum homocysteine is associated with an increased risk of coronary artery disease.[3] Among individuals with type 2 diabetes elevated plasma homocysteine levels are associated with an increased risk of macroangiopathy and nephropathy.[4] It is unclear if this increased risk is due to the homocysteine itself, the methanol which is produced as a by-product of homocysteine biosynthesis, or some other mechanism which is correlated with homocysteine biosynthesis. Some authors believe that methanol causes arteriosclerosis.[5] Other authors believe that arteriosclerosis is caused by homocysteine via some direct but yet to be explained mechanism.[6]

Chronic infection

Elevated serum homocysteine levels, in spite of normal dietary methionine intake, may therefore suggest a chronic infection.

See also

References

External links

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