Today is our topic of discussion Classification of protein
Classification of protein
According to structure:
Simple protein –
The protein which gives only amino acid on breakdown.
Compound or conjugated ptotein-
The protein which gives other non-protein substance in addition to amino acid on breakdown. Example – lipoprotein, glycoprotein, phosphoprotein etc.
Derived proteins –
These are the substances resulting from the decomposition of simple and conjugated proteins. These include coagulated proteins, peptones and peptides.
According to source:
1. First class proteins: These are proteins of high biological value containing all the essential amino acids. Sources – Animal sources such as, meat, fish, egg, milk etc.
2. Second class proteins: These are proteins of low biological value with poor in essential amino acids. Sources – Vegetable sources such as pulses, cereals, nuts, oil seed etc.
According to function:
1. Enzymes are protein in nature that catalyzes chemical and biochemical reactions within and outside the living cell.
2. Hormones Protein hormones are responsible for regulation of many processes in the organisms. Protein hormones are: insulin, prolactin etc.
3. Transport proteins These proteins are involved with transporting some other chemical compounds. Examples are: haemoglobin and myoglobin (present in muscle) – oxygen transport; albumin – fatty acid transport in the blood stream, transmembrane proteins etc..
4. Immunoglobulin or Antibodies – Proteins that are involved with immune response of the
organism to neutralize large foreign molecules, which can be a source of an infection.
5. Structural proteins – These proteins maintain structures of other biological components, like
cells and tissues. Example: Collagen, elastin, a-keratin – these proteins are involved in the formation of the whole body.
6. Motor protein – These proteins can convert chemical energy into mechanical energy in muscle cells during their action.
7. Receptor proteins – These proteins are responsible for signal detection and translation into other type of signal. Example – rhodopsin (light detecting protein), many transmembrane proteins are receptor proteins.
8. Storage proteins – These proteins contain energy, which can be released during metabolic processes in the organism. Egg albumin and milk casein are such proteins.
Requirement of protein:
About 15 percent of our daily calorie should come from protein. As a general guideline, the recommended dietary allowance (RDA) for protein for adults is 0.8 grams per Kg body weight per day.
Requirement of protein according to age, gender and life stage group
See also :