Alanine has an important function in our body’s energy production and muscle building, as our muscle fibers are made up of about 6 percent alanine. It is also present in high concentrations in prostatic fluid and influences the sensitivity of cells to insulin.
Arginine is also involved in muscle building by promoting growth hormones. It is also the basis for the body’s synthesis of the neurotransmitter nitric oxide (NO) and is therefore of vital importance for our blood circulation, vascular health and cardiovascular system. In addition, arginine stimulates the build-up of collagen and creatine (the building block of our hair fibers) as well as the formation of white blood cells.
Asparagine plays an important role in the body’s detoxification process as well as in the breakdown of alcohol in the blood, as it stimulates kidney production. It is considered to be a blood purifier and diuretic. Asparagine is also a precursor of chemical messengers (neurotransmitters).
As one of the most important messenger substances in the brain, aspartic acid influences our mental and physical performance. In addition, aspartic acid is a precursor for other neurotransmitters as well as a precursor of coenzyme A, which is involved in the breakdown of fatty acids. It also serves as an energy source for the cells of the intestinal mucosa.
Cysteine plays a major role in the formation of cartilage, bones, skin, hair and nails. While babies still have to absorb cysteine – at least in part – from food, it is later produced independently by the liver from the essential amino acid methionine and the non-essential amino acid serine. Cysteine is a precursor of taurine, which is important for the nervous system, visual cells and heart function; together with vitamin B, it is involved in the formation of fat cells.
With a share of about 20%, glutamine is the most important free amino acid in the blood plasma in terms of quantity. It is found in almost every cell and functions as an important source of energy, especially for the cells of the digestive system and immune defense. Glutamine is also present in high concentrations in muscle cells, which also predominantly synthesize it.
Glutamic acid is the amino acid with the highest concentration in the brain. It is the starting material for the neurotransmitter glutamate, which is involved in the urea cycle and has a calming effect on the nervous system as a precursor of the neurotransmitter GABA. Glutamic acid is involved in the formation of the amino acids arginine and proline and in the formation of glutathione. It binds the cell toxin ammonia and thus also plays an important role in detoxification.
Glycine is involved in the body’s own formation of glutathione and, as a component of hemoglobin metabolism, in the transport of oxygen in the blood. It accounts for about one third of the protein content of collagen, making it an important component of skin, hair, cartilage, tendons, ligaments and joints. To regulate blood sugar levels, the body can convert glycine into glucose. Glycine, together with taurine, regulates the leakage of bile acid from the gallbladder into the small intestine. It also belongs to the neurotransmitters, whereby it has a calming or inhibiting effect.
Histidine is involved in the formation of the iron storage protein ferritin and is a component of the red blood pigment hemoglobin. It is particularly important for the transport of oxygen in the body and for buffering the pH value in our blood. Our body produces the neurotransmitter histamine from histidine, which plays a central role in immune defense against foreign substances and is released in excess in allergies.
As a component of collagen, proline plays an important role in cell renewal, tissue repair and the regeneration of cartilage and bone. It protects our body from collagen breakdown by blocking the so-called collagenases, the enzymes that break down connective tissue. In combination with vitamin C, our body can form the related hydroxyproline from proline, which is also an important component of the structural proteins collagen and elastin. Proline itself is synthesized from glutamate, the salt of glutamic acid.
Serine is found in the two digestive enzymes trypsin and chymotrypsin as well as in many membranes. It is present in particularly high concentrations in the cell membranes of the brain. It plays an important role in the transmission of stimuli by neurons and is therefore essential for our memory and attention. It can be synthesized from glycine or threonine.
Selenocysteine is the most recently discovered amino acid. It is a central component of many enzymes, for example deiodase, which activates the thyroid hormone. It contains the trace element selenium and protects the body against oxidative stress. Selenocysteine is formed by modification of the essential amino acid serine.
Tyrosine is necessary, among other things, for the formation of the stress hormones adrenaline and noradrenaline, the skin pigment melanin, individual thyroid hormones and the neurotransmitter dopamine. People with the inborn error of metabolism phenylketonuria (PKU) cannot metabolize the essential amino acid phenylalanine, the precursor of tyrosine, to tyrosine due to a missing enzyme.