Classification of proteins

Classification of proteins

    Proteins are biochemically classified into three groups based on their chemical composition. They are simple proteins, conjugated proteins and derived proteins.
    1.Simple proteins
    On hydrolysis simple proteins yield only amino acids.
    eg. Albumins, globulins, glutelins, prolamins, fibrous protein and histamines
    2. Conjugated Proteins
    On hydrolysis conjugated proteins give a protein fraction and a non-protein fraction
    eg. haemoglobin, nucleoprotein, glycoprotein and lecithoprotein
    3. Derived Proteins
    Derived proteins are derived from a mother protein either through hydrolysis or digestion
    eg. metaprotein, coagulated proteins, peptides and peptones
    Nutritional classification of Proteins
    Proteins are classified into complete proteins, partially incomplete proteins and incomplete proteins based on the presence of essential amino acids in them.
    Complete Protein
    A complete protein food contains all essential amino acids in proper proportion. It helps the protein to promote growth, maintenance and repair,
    eg. Milk, egg and fish
    Classification of proteins Classification of proteins Classification of proteins

    Partially Incomplete Proteins
    Partially incomplete proteins lack one or more essential amino acids and hence will help to maintain the body but cannot promote growth.
    eg: red gram, peas and green gram
    Classification of proteins

    Incomplete proteins
    Incomplete proteins neither help maintenance nor growth.
    eg. Zein in maize
    Nutritional classification of amino acids
    Essential amino acids
    Essential amino acids are ones that cannot be synthesized by the body at a rate sufficient to meet the needs for growth and maintenance.
    eg. Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine
    Non essential amino acids
    Non essential amino acids are ones that the body can make in adequate amounts if nitrogen is available in the diet.
    eg. Alanine, aspartamine, aspartic acid, glutamic acid, glutamine and serine
    Conditionally essential amino acids
    Conditionally essential amino acids are needed in the diet unless precursors are available for the synthesis. The new born may not have enzymes in adequate amounts to synthesize nonessential amino acids or in intestinal metabolic dysfunction arginine may not be synthesized.
    eg. Histidine, arginine, cysteine, glycine, proline and tyrosine

Last modified: Monday, 4 June 2012, 4:53 AM