It’s probably no secret that aminocarboxylic acids (amino acids) are beads in a complex protein chain of any living organism. But few people know that almost all of them were discovered in the second half of the last century.
The biogenic sulfur-containing amino acids that interest us in this article are cysteine and methionine. Let’s try to enrich the reader’s knowledge of these two organic compounds in terms of the biochemistry and biology of our health.
The bricks that make up the protein
Amino acids (including sulfur-containing) are organic compounds that are quite widely represented in nature. Today we know more than 500 amino acids. At the same time, 240 of them are found in the environment in a free form, and all the rest are intermediate products of metabolic processes in living organisms.
And today it remains a mystery why, out of all this diversity, only 20 amino acids are found in human proteins (pictured above). They are called biogenic, or involved in protein biosynthesis. Among these "chosen ones", only two are sulfur-containing amino acids. These are methionine (Methionine) and cysteine (Cysteine), which contain a sulfur atom.
All amino acids for our body are divided into two groups: essential (those that are not synthesized in the human body) and interchangeable (those that the body can produce itself). Cysteine belongs to the second group, but methionine - to the first, which we must receive with food - pathologies are associated with it, which are caused by a violation of the metabolism of sulfur-containing amino acids. But first things first.
What is C5H11NO2S?
In its pure form, methionine is a colorless crystal that smells rather unpleasant and soluble in water. This is an amino acid that in our body serves as a supplier of methyl groups and sulfur. As already mentioned, methionine is an indispensable sulfur-containing amino acid and is not synthesized in the body.
It comes with food and is used by our cells to collect its own proteins on ribosomes. This sulfur-containing amino acid is found in milk protein (casein), in eggs, sesame, flour, pork and chicken, fish (salmon and tuna), in wheat and oats, in legumes, in all green vegetables, in parmesan cheese and mozzarella.
In addition, modern pharmacology has in its arsenal drugs that are absolutely identical to methionine. Due to its role in protein synthesis and fat-soluble properties, these products are widely used in the sports field.
The value of methionine for the body
The biochemistry of the exchange of sulfur-containing amino acids supplies our body with sulfur and methyl groups. This amino acid plays a significant role in the synthesis of cysteine, taurine, adrenaline and melatonin.
Its functions in the body are diverse and quite wide:
- Participates in lowering cholesterol and helps prevent atherosclerosis.
- It acts as a hepatoprotector - protects the liver from the deposition of excess fat, restores its structure.
- Beneficial effect on the condition of the kidneys and excretory system.
- It acts as an antidepressant, restores and normalizes sleep, eliminates chronic fatigue.
- Improves the condition of the skin, nails and hair.
- It is able to neutralize toxic metals, free radicals and thus provide intoxication of the body.
- Improves the condition of the joints. It is proved that in patients with arthritis, the amount of sulfur in the cartilage is reduced by 3 times compared with the norm.
And this is not a complete list. It is believed that to provide our body with this amino acid, it is necessary to receive 19 mg of methionine per 1 kg of weight per day.
C3H7NO2S - tread and cleaner
Cysteine is an amino acid that is synthesized in our body from methionine. This process is multistage and occurs in the presence of specific enzymes, vitamins. A failure in it can occur at each stage, and this is also associated with pathologies of the exchange of sulfur-containing acids.
Derivatives of cysteine breakdown are taurine and glutathione. The first is a protein that is responsible for the adequate functioning of the brain, and the second plays an important role in the functioning of the immune system. Cysteine itself affects the skin condition (responsible for collagen synthesis) and detoxification processes. It is also part of many digestive tract enzymes.
Value for the body
It should be noted such positive functions of this amino acid:
- Cysteine improves hair growth, providing collagen synthesis, which positively affects the formation of the skin, the structure of nails.
- This sulfur-containing amino acid affects muscle formation and fat burning.
- It acts as an antioxidant, eliminating toxins, especially while taking vitamin C and selenium.
- It activates white blood cells and lymphocytes, affecting their antiviral, antitumor, anti-inflammatory properties.
The daily rate of cysteine for a healthy adult is up to 3 grams per day. In this case, increasing the dose can lead to toxic poisoning.
Beautiful color reaction
It is easy to determine the presence of methionine and cysteine, and this experience is often shown in high school. The reaction to sulfur-containing amino acids (Fole's reaction) is one of the few named, beautiful and spectacular chemical transformations.
It is done like this. In a test tube containing lead acetate (1 ml), 10% sodium hydroxide solution and chicken protein are added. Then the mixture is heated. A black precipitate appears in the test tube, and the darker it is, the more sulfur-containing amino acids are in the solution.
The reaction is based on the decomposition of sulfur with alkali to form hydrogen sulfide, which binds to sodium and precipitates.
The reaction is widely used in clinical and biological research, pharmaceuticals.
Deficit conditions
Homocystinuria is a hereditary pathology for the exchange of sulfur-containing amino acids. It affects the nervous, musculocutaneous, and vascular systems, accompanied by a lag in mental development, seizures, pathologies of the lens of the eye and optic nerves, and disorders in the formation of the skeleton and muscles.
The frequency of pathology is 1 case per 100 thousand newborns. In the case of early diagnosis of this type of enzyme, treatment includes a diet with the exception of methionine and vitamin therapy.
This is not the only pathology for the exchange of sulfur-containing amino acids, but the rest are even more rare.
Acquired Violations
Deficit states usually manifest themselves in the form of brittle nails, hair loss, swelling of soft tissues, exacerbations of heart, liver, and kidney diseases.
For people with increased acidity of the stomach, taking methionine-rich foods is practically contraindicated. Excess of it in the body causes allergies, drowsiness and digestive disorders.
But under stress and physical exertion, our body requires an increase in sulfur-containing amino acids in the diet. In addition, pregnant women should not neglect foods rich in them. This is the key to the normal formation of the nervous system in the fetus.
Weight loss assistant
In the five amino acids that will help lose weight, cysteine is not the last place.
This amino acid signals the brain that the stomach is already full. Thanks to cysteine, we feel full. And this leads to the prevention of overeating, weight loss and increase the speed of weight loss.
Eat broccoli, oatmeal with bananas, eggs, sea fish - and this anorexigenic amino acid will help to achieve a slim figure.