Serine is biosynthesised from a glycolytic intermediate, 3-phosphoglycerate (3-PG), in a three-step process involving the enzymes: 3-phosphoglycerate dehydrogenase, phosphoserine aminotransferase, and phosphoserine phosphatase. it can also be derived in a reversible reaction from glycine; through degradation of protein and phospholipids and through dietary intake.
Serine plays a role in cell growth and development (cellular proliferation). The conversion of L-serine to glycine by serine hydroxymethyltransferase results in the formation of the one-carbon units necessary for the synthesis of the purine bases, adenine and guanine. These bases when linked to the phosphate ester of pentose sugars are essential components of DNA and RNA and the end products of energy producing metabolic pathways, ATP and GTP. In addition, serine conversion to glycine via this same enzyme provides the one-carbon units necessary for production of the pyrimidine nucleotide, deoxythymidine monophosphate, also an essential component of DNA.
Serine is a precursor for the neurotransmitters glycine and D-serine and indirectly through cysteine, for the neurotransmitter taurine. Cysteine, which can be formed from serine through the trans-sulphuration pathway, is the precursor for proteins, glutathione, taurine, coenzyme A and inorganic sulphate.
Serine and the brain, mental health and nerves
The condensation of serine with palmitoyl-CoA is the first step in the synthesis of sphingosine. Sphingosine serves as the core of sphingolipids, which include the sphingomyelins (primarily in brain and other nervous tissue) and glycosphingolipids. Sphingolipids are abundant in the myelin sheath and are present in all membranes. Phosphatidylserine, which is derived from L-serine, is an important messenger for apoptosis. Apoptosis, or programmed cell death, plays a critical role in the normal development of the nervous system.
Serine plays roles in protein, fatty acid, genetic code carriers (DNA and RNA) synthesis, and muscle build-up. Serine is a constituent in the brain and protective covers of nerves. Therefore, it is an important amino acid for the proper functioning of the brain and nervous system. Furthermore, serine boosts healthy immune system by aiding the production of antibodies. It is also a component of all cell membranes.
Additional serine health benefits come indirectly through its effect on other biochemicals. For example, serine is a precursor to produce amino acids such as glycine, cysteine and tryptophan. Tryptophan, necessary for the synthesis of serotonin and functioning of neurotransmitters, is known to help relieve stress, anxiety and depression.
L-serine regulates the release of several cytokines in the brain under some neuropathological conditions to recover cognitive function, improve cerebral blood flow, inhibit inflammation, promote remyelination and exert other neuroprotective effects on neurological injury,
Serine and cancer
Researchers have found that the development of lymphoma and intestinal cancer slowed in mice fed a diet without serine and glycine. However, because these amino acids are naturally made by the body and are found in so many foods it would be impossible to avoid them in the diet. More studies are underway to find if there is a way to inhibit them from cancerous cells.
Serine deficiency
Deficiency symptoms include slow or delayed cognitive and physical skills (psychomotor retardation), seizures and microcephaly. Microcephaly refers to health condition in which the head size is smaller than normal and is caused by underdevelopment of the brain. Serine deficiency is a rare, inherited, metabolic disorder of L-serine biosynthesis. Children with apparent neurological disorders are rarely, if ever, tested for a metabolic disorder and unlikely to be tested for serine deficiency. It is likely that serine deficiency is grossly under-diagnosed.
Symptoms of children with serine deficiency
- Cerebral palsy
- Congenital microcephaly (small head size from birth)
- Cortical blindness
- Cortical visual impairment (limited vision due to brain involvement rather than a primary eye disorder)
- Epileptic encephalopathy
- Encephalopathy
- Epilepsy
- Failure to thrive
- Hypotonia (also known as “floppy infant syndrome,” is a medical term for decreased or poor muscle tone)
- Megaloblastic anaemia
- Muscle weakness
- Poor brain growth
- Poor head control
- Reflux
- Seizures
- Spastic quadriparesis (spasticity or stiffness and muscle weakness at the same time), infantile spasms
- White matter abnormalities (brain)
In particular, the triad of congenital microcephaly, spastic quadriparesis (cerebral palsy) and seizures should be an important clue to test for this disorder.
Natural sources of serine in alphabetical order
- Algae and seaweed
- Almonds
- Apples
- Apricots
- Asparagus
- Beef
- Buckwheat
- Chickpeas
- Cow’s milk
- Egg whites
- Goat’s milk
- Lentils
- Organ meats
- Oily fish
- Peanuts
- Pumpkin seeds
- Quinoa
- Sesame seeds
- Shellfish (highest source)
- Soybeans
- Venison
- Walnuts
Related nutrients
Related subjects
- Allergies
- Asthma
- Bone and joint disorders (arthritis, osteoporosis and rheumatism)
- Brain and mental health disorders
- Cancer
- Dementia (Alzheimer’s disease)
- Diabetes
- Epilepsy
- Fibromyalgia
- Gout
- Hay fever
- Heart disorders (atherosclerosis and heart attacks)
- Nature cures for babies
- Nervous system disorders
- Obesity
- Pain and inflammation
- Parkinson’s disease
- Pregnancy and childbirth
- Skin disorders
- Stroke
- Vitamin B9
References
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