Classification of proteins and amino acids

  Proteins and amino acids can be classified based on different criteria. Here are some common classifications: Classification of Proteins: ...

 

Proteins and amino acids can be classified based on different criteria. Here are some common classifications:

Classification of Proteins:

a. Structural Proteins: 

These proteins provide support and structure to cells and tissues. Examples include collagen, keratin, and elastin.

b. Enzymes: 

Proteins that act as catalysts in biochemical reactions. They facilitate the conversion of substrates into products. Examples include amylase, lipase, and catalase.

c. Transport Proteins: 

These proteins facilitate the transport of molecules and ions across cell membranes or within the bloodstream. Hemoglobin and albumin are examples of transport proteins.

d. Hormones: 

Proteins that act as chemical messengers, regulating various physiological processes. Examples include insulin, growth hormone, and thyroid-stimulating hormone.

e. Antibodies: 

Proteins involved in the immune response, recognizing and neutralizing foreign substances (antigens) in the body.

f. Contractile Proteins: 

Proteins responsible for muscle contraction. Actin and myosin are crucial contractile proteins in muscle cells.

g. Storage Proteins: 

Proteins that store essential molecules, such as nutrients or metal ions. Examples include ferritin (iron storage) and casein (milk protein).

h. Regulatory Proteins: 

Proteins involved in controlling gene expression and cellular processes. Examples include transcription factors and protein kinases.

Classification of Amino Acids:

a. Essential Amino Acids: 

These are amino acids that cannot be synthesized by the body and must be obtained from the diet. Examples include leucine, valine, and lysine.

b. Nonessential Amino Acids: 

These amino acids can be synthesized by the body, and there is no dietary requirement for them. Examples include alanine, glycine, and serine.

c. Conditionally Essential Amino Acids: 

These amino acids are usually nonessential but may become essential under certain conditions, such as during illness or growth. Examples include arginine and cysteine.

d. Polar Amino Acids: 

Amino acids with polar side chains that interact with water molecules. Examples include serine, threonine, and glutamine.

e. Nonpolar Amino Acids: 

Amino acids with nonpolar side chains that are hydrophobic and tend to cluster together in the interior of proteins. Examples include alanine, leucine, and valine.

f. Acidic Amino Acids: 

Amino acids with acidic properties due to the presence of a carboxyl group. Examples include aspartic acid and glutamic acid.

g. Basic Amino Acids: 

Amino acids with basic properties due to the presence of an amino group. Examples include lysine, arginine, and histidine.

Amino acids can be classified based on various criteria. Here's a detailed classification of amino acids:

Based on Side Chain Properties:

a. Non-Polar Amino Acids:

• Glycine (Gly)
• Alanine (Ala)
• Valine (Val)
• Leucine (Leu)
• Isoleucine (Ile)
• Methionine (Met)
• Phenylalanine (Phe)
• Tryptophan (Trp)
• Proline (Pro)

b. Polar Amino Acids:

• Serine (Ser)
• Threonine (Thr)
• Cysteine (Cys)
• Tyrosine (Tyr)
• Asparagine (Asn)
• Glutamine (Gln)

c. Positively Charged (Basic) Amino Acids:

• Lysine (Lys)
• Arginine (Arg)
• Histidine (His)

d. Negatively Charged (Acidic) Amino Acids:

• Aspartic Acid (Asp)
• Glutamic Acid (Glu)

Based on Biosynthesis:

a. Essential Amino Acids (cannot be synthesized in the body and must be obtained from the diet):

• Phenylalanine (Phe)
• Valine (Val)
• Threonine (Thr)
• Tryptophan (Trp)
• Isoleucine (Ile)
• Methionine (Met)
• Leucine (Leu)
• Lysine (Lys)
• Histidine (His)

b. Non-Essential Amino Acids (can be synthesized in the body):

• Alanine (Ala)
• Arginine (Arg)
• Asparagine (Asn)
• Aspartic Acid (Asp)
• Cysteine (Cys)
• Glutamic Acid (Glu)
• Glutamine (Gln)
• Glycine (Gly)
• Proline (Pro)
• Serine (Ser)
• Tyrosine (Tyr)

Based on Role in Protein Synthesis:

a. Coding Amino Acids (encoded by the genetic code and incorporated into proteins)

b. Non-Coding Amino Acids (involved in protein folding, modification, and other cellular processes)

Based on Function:

a. Hydrophobic Amino Acids (contribute to protein stability in hydrophobic environments)

b. Hydrophilic Amino Acids (contribute to protein solubility and interaction with water)

table illustrating the classification of proteins and amino acids with examples:

Classification	Proteins	Amino Acids
Structural Proteins	Collagen	Alanine, Glycine, Proline
Enzymes	Amylase	Serine, Aspartic Acid, Glutamic Acid
Transport Proteins	Hemoglobin	Lysine, Histidine, Valine
Hormones	Insulin	Tryptophan, Phenylalanine, Tyrosine
Antibodies	Immunoglobulin G (IgG)	Cysteine, Methionine, Arginine
Contractile Proteins	Actin, Myosin	Leucine, Isoleucine, Valine
Storage Proteins	Ferritin	Glutamine, Asparagine, Threonine
Regulatory Proteins	Transcription Factors	Glutamic Acid, Lysine, Serine