University:
Liberty University
Course:
BIOM 500 | Introduction to Biomedical Sciences
Academic year:

2024
Views:

448

Pages:

8
Author:

Sheha A.

Classification of Proteins Proteins can be classified on the basis of their composition, shapes, and functions. Based on the composition of proteins: a) Simple Proteins: These contain only one amino acid. Do not contain any additional groups. Ex: Serum albumin, serum globulin, keratin, etc. (except insulin) b) Conjugated Proteins: These contain additional chemical groups. Ex: Hemoglobin (contains heme group), glycoproteins (containing carbohydrates) Lipoproteins (containing lipids) Hemoglobin (heme protein containing heme as a conjugate group) Casein (phosphoprotein containing phosphate as a conjugate group) Immunoglobulins (glycoproteins, containing carbohydrates as a conjugate group) c) Derived proteins: These are the partial degradation products of simple or compound proteins. Ex: Gelatin derived from the collagen iii) Classification based on the state These are 2 types: Globular Proteins: These are spherical or oval in shape. Ex: Hemoglobin, Albumin, and enzymes. Fibrous Proteins: These are elongated and fiber-like structures. Ex: Keratin, Collagen, Elastin, etc. iii) Based on the biological function: Proteins have diverse functions, classified based on their biological role. Catalytic Proteins: All enzymes are proteins which catalyze reactions in nature. (Exception is Ribozyme, which is RNA) Ex: Hexokinase, Amylase, etc. Defense Proteins: Ex: Immunoglobulins or antibodies. Storage Proteins: Ex: Keratin present in hair and nails, Collagen present in bones and muscles. Hormonal Proteins: Some hormones are proteins. Ex: Growth hormone, Insulin, etc. 5. Contractile Proteins: Actin, Myosin, and Tropomyosin present in muscles. 6. Transport Proteins: Ex: Serum albumin, Haemoglobin, Channels, carriers, etc. Facilitate the transport of substances. 7. Storage Proteins: Ex: Ferritin stores iron in the liver and bone marrow. 8. Visual Proteins: Ex: Rhodopsin and Iodopsin present in the retina of the eye. 9. Membrane Proteins: Ex: Sodium Potassium Pump or Sodium Potassium ATPase. 10. Haemostatic Proteins: Ex: Fibrinogen, Prothrombin, etc. 11. Buffer Proteins: Ex: Plasma proteins, hemoglobin. 12. Respiratory Proteins: Ex: Hemoglobin, myoglobin.