To understand proteins better, you need to know about amino acids. Although there are more than 300 amino acids used in the body, only 8 of these are essential in the diet of adults. One amino acid, histidine, is essential in the diet of infants and children.
Proteins are made up of essential amino acids. The word essential means that these amino acids (compared with other amino acids) cannot be made by the body, but must be obtained from the diet. It also means that without these amino acids normal health and wellbeing are not possible. The other amino acids can be made in the body of adults from the basic eight:
Valine
Leucine
Isoleucine
Methionine
Tryptophan
Lysine
Phenylalanine and
Threonine
Branched-chain Amino Acids (BCAA)
Chemically, branched-chain amino acids have side chains.
Valine
Leucine
Isoleucine
Sulphur Amino Acids
methionin
Non essential:
cystine and
cysteine
Free-form Essential Amino Acids
Tryptophan
Lysine
Phenylalanine and
Threonine