How Many Amino Acids Are in Proteins

There are probably hundreds of different amino acids found in nature, but only twenty are incorporated into the proteins found in living things (Table 6.1). This means that these twenty amino acids are the basis of protein found in birds, lizards, plants, bacteria, fungi, yeast, and so on. This is a very profound and also convenient situation. First, it allows us to further appreciate that, despite the obvious structural and functional differences between the different life-forms on this planet, there is common ground and more than likely common ancestry. Second, it somewhat simplifies human nutrition as we are able to obtain all of the amino acids we need to make our body proteins by eating the proteins of other life-forms.

Table 6.1 The Twenty Amino Acids Used to Make Proteins

Essential Amino

Nonessential

Acids

Amino Acids

Tryptophan

Alanine

Valine

Proline

Threonine

Tyrosine

Isoleucine

Cysteine

Leucine

Serine

Lysine

Glutamine

Phenylalanine

Glutamic acid

Methionine

Glycine

Arginine*

Asparagine

Histidine*

Aspartic acid

  • Essential during growth.
  • Essential during growth.

H-«-CH—I-OH HaN-CH—C-OH W-ÇH—i ÎH—C-OH HjN-CH—C-OH HjN-ÇH—C-OH c-OH

Amino acids with 'R' groups not having a charge

Amino acids with large bulky 'R' groups

Glycine

CH3 Alanine

Amino acids with large bulky 'R' groups

Phenylalanine

Phenylalanine

Tyrosine

Tyrosine

Amino acids with partially charged 'R' groups

H2N-CH—C-OH H2N-CH—C-OH H2N-CH—C-OH HgN-CH—C-OH HgN-CH—C-1

CHj, OH

Serine

Cysteine I Asparagine

0 0

Post a comment