Serine
Overview
Serine is an amino acid in food protein. Human cells also make it. This page is for serine as the cosubstrate of cystathionine beta-synthase, the enzyme that condenses serine with homocysteine to form cystathionine on the transsulfuration path.
The human enzyme uses serine in that condensation. Kinetic work on the recombinant enzyme and the crystal structure both place serine at that step, together with the pyridoxal-phosphate cofactor [1,2]. Endogenous synthesis and diet can both supply serine. That substrate role does not show that eating more serine, or more protein, increases cystathionine formation [1].
Dietary Origin
Serine in food is the amino acid in protein. The enzyme evidence is recombinant human cystathionine beta-synthase and its structure, not a meal [1,2]. A food that contains serine therefore has a composition relationship only. No food page here has a verified serine amount linked as the cause of a change in cystathionine formation.
Research Spotlights & Evidence Checks
Recipes
Foods
Biological Regulatory Systems
| Biological Regulatory System | Evidence-qualified relationship | Evidence |
|---|---|---|
| Methylation & One-Carbon Metabolism (BRS2) | Serine is the cosubstrate of cystathionine beta-synthase in the transsulfuration pathway. Endogenous synthesis and diet can both supply it. Dietary serine is not shown to increase cystathionine formation. | [1,2] |
References
[1] Belew et al. (2009). Kinetic characterization of recombinant human cystathionine beta-synthase purified from E. coli. Kinetic evidence that recombinant human cystathionine beta-synthase uses serine with homocysteine. Enzyme assay, not a dietary trial.
[2] Meier et al. (2001). Structure of human cystathionine beta-synthase: a unique pyridoxal 5'-phosphate-dependent heme protein. Crystal structure of the human enzyme, including its pyridoxal-phosphate cofactor. Structure, not evidence that dietary serine increases flux.