Proteins, the building blocks of life, are everywhere. They are the main components in our hair, skin, muscles, and connective tissues. They play vital roles in our bodies, from aiding in digestion to fighting diseases. Yet, many of us are not fully aware of what proteins are and how they function in our bodies.
What Are Proteins?
Proteins are complex molecules that are vital for the structure, function, and regulation of the body's tissues and organs. They are made up of smaller units called amino acids, which are linked together in long chains. There are 20 different types of amino acids that can be combined to make a protein. The sequence of amino acids determines each protein's unique 3-dimensional structure and its specific function.
Classification of Proteins
Proteins can be classified based on their function, shape, and chemical composition. Let's delve into each of these categories.
Functional Classification
Enzymes These proteins speed up chemical reactions in the body.
Hormones These proteins act as chemical messengers, transmitting signals throughout the body.
Transport Proteins These proteins move molecules and nutrients around the body.
Storage Proteins These proteins store amino acids for later use.
Structural Proteins These proteins provide structure and support for cells.
Shape-based Classification
Fibrous Proteins These proteins have a long and narrow shape, providing structural support.
Globular Proteins These proteins are compact, generally rounded, and soluble in water.
Chemical Composition-based Classification
Simple Proteins These proteins are composed only of amino acids.
Conjugated Proteins These proteins are joined to other molecules like sugars, lipids, nucleic acids, metals, etc.
Types of Simple Proteins
There are several types of simple proteins, each with unique characteristics and functions:
Protamines These are simple proteins that yield a small number of amino acids upon hydrolysis. Protamines are found in the reproductive tissues of certain species.
Histones These proteins are more complex than protamines and are found in red blood cells, white blood cells, and sperm cells.
Albumins These are the most common proteins in the body. They are soluble in water and can be found in various body fluids and tissues.
Globulins These proteins are abundant in the animal and plant kingdoms. They are not soluble in water but are soluble in salt solutions.
Glutelins These proteins, along with prolamins, constitute the majority of the protein reserve in grains.
Prolamins These proteins are rich in the amino acid proline and are found in many grains.
Phosphoproteins These proteins are rich in phosphoric acid and are predominantly found in animal proteins.
Scleroproteins These proteins, also known as albuminoids, are found exclusively in the animal kingdom and are known for their mechanical functions.
Conjugated Proteins
Conjugated proteins consist of a simple protein chemically joined to a non-protein group called a prosthetic group. Depending on the type of prosthetic group, conjugated proteins can be classified into glycoproteins, lipoproteins, phosphoproteins, and chromoproteins.
