amino acids are the fundamental units of all proteins. They exist 20 many different types of amino acids forming these important macromolecules, each with specific properties. It is important to highlight that, regardless of the living being studied, all had their proteins formed by the same 20 amino acids.
Next, we'll talk more about these organic molecules, emphasizing their structures, the 20 types of amino acids that make up proteins, and their classification.
→ Definition of amino acids
Amino acids can be defined as organic molecules that present groups — carboxyl (-COOH) and amino (-NH3) — turned on The a single carbon, called alpha carbon.This carbon is observed in the center of the amino acid and binds to the group amino, to the group carboxyl, to one hydrogen atom and to one variable group, which is called side chain or R group.
The central carbon is called the alpha carbon and is linked to an amino group, a carboxyl group, a hydrogen atom and the R group.
Read too:Organic Functions in Amino Acids
→ The 20 amino acids found in proteins
Let's look at the list of the 20 amino acids found in proteins and their abbreviations, in three letters and one letter:
amino acid |
three letter abbreviation |
one letter abbreviation |
Alanine |
Allah |
THE |
arginine |
Arg |
R |
asparagine |
asn |
N |
aspartic acid |
Asp |
D |
glutamic acid |
Glu |
AND |
Cysteine |
Cys or Cis |
Ç |
Glycine |
Gly or Gly |
G |
glutamine |
Gln |
Q |
Histidine |
His |
H |
isoleucine |
Ile |
I |
leucine |
read |
L |
Lysine |
Lys or Lys |
K |
Methionine |
Met |
M |
Phenylalanine |
Phe or Fen |
F |
proline |
Pro |
P |
Serine |
To be |
s |
Tyrosine |
Tir or Tyr |
Y |
threonine |
Tre or Thr |
T |
tryptophan |
Trp |
W |
Valine |
Val |
V |
→ Amino acid classification
Amino acids are generally grouped according to the characteristics of their side chains. According to these characteristics, we can divide them into:
Amino acids with non-polar side chains;
Amino acids with polar side chains;
Acidic amino acids (amino acids that have negatively charged side chains due to the presence of carboxyl groups);
Basic amino acids (amino acids that have the amino group in the side chains).
Note that the 20 amino acids are grouped according to the property of their side chains.
In addition to this classification, amino acids can be classified into two groups: essential and non-essential amino acids. In this case, the criterion used is the body's ability to synthesize these amino acids.
The amino acids called essential are those that cannot be synthesized endogenously and must be obtained from the food, already the amino acids non-essential are those that the organism is able to synthesize.
Amino acids can be found in many foods, such as red meat, eggs, cheese, beans, lentils, almonds, peanuts and rice.
→ essential amino acids
The so-called essential amino acids are those that must be obtained through food, due to the fact that the body is not able to synthesize them. The following are considered essential amino acids: isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. In children, one more amino acid is considered essential: histidine.
Note the structure of essential amino acids and arginine (*), a conditionally essential amino acid.
It is worth noting that the arginine is considered an amino acid conditionally essential. This is due to the fact that, under normal conditions, the organism is able to produce it in an adequate quantity, however, in In certain clinical situations, there is an increased consumption of this amino acid, so that it exceeds the body's capacity to produce it.
A curious fact about essential amino acids is that all of them can be obtained through the ingestion of a very famous dish among Brazilians: rice and beans.
Beans are a food that has all the essential amino acids, but has a limited amount of methionine and cysteine. Rice, in turn, is rich in methionine and cysteine. In this way, the combination becomes perfect.
→ Amino Acid Function
Amino acids are important molecules that act as subunits in the construction of proteins. At proteins they are essential macromolecules for living beings, acting, among other functions, in the body defense, at cell communication, at the substance transport, at movement and contraction in certain structures, It is like chemical reaction catalysts (enzymes).
→ Amino Acids and Proteins
As we know, amino acids are important in the formation of proteins. Each of these macromolecules is made up of a long chain of amino acids, which are linked through peptide bonds.
Each protein is formed by a specific sequence of amino acids, which sequence will determine its three-dimensional conformation.
The 20 different types of amino acids that exist combine in different ways, giving rise to different proteins. A protein has, on average, between 50 and 2000 amino acids.
Read too: Function of proteins and their sources in food
By Ma. Vanessa Sardinha dos Santos