Proteins, Uses, Types of Proteins, Importance, Classification, Protein Rich Foods

THE BEGUSARAI POST

PROTEINS AN INTRODUCTION

Proteins are defined as the building blocks of life. Proteins are the most diverse class of biomolecules, both structurally and functionally, and have evolved to accomplish many tasks in living systems. The variety of structures and sizes is quite remarkable. Gro EL is a large, barrel shaped protein consisting of 14 subunits and an overall molecular weight of 840,000 that assists in protein refolding. Very small proteins, generally labelled antimicrobial peptides (AMPs), ranging from 15-50 amino acids function as part of the innate immunity in multicellular organisms

Table Of Content

• What are Proteins
• Importance of Proteins
• Classification of Proteins
• Foods containing Protein

WHAT ARE PROTEINS?

Proteins may be defined as the high molecular weight mixed polymers of α-amino acids joined together with peptide linkage (-CO-NH-).

Proteins are the chief constituents of all living matter. They contain carbon, hydrogen, nitrogen and sulphur and some contain phosphorus also.

Importance of proteins

Proteins are the essence of life process.

• They are the fundamental constituents of all protoplasm and are involved in the Structure of the living cell and in its functions.
• Enzymes are made up of proteins
• Many of the hormones are Proteins.
• The cement substances and the reticulum,  which bind or holds the cells are tissue or organs are made up partly of proteins
• They execute their activities in the transport of oxygen and carbon dioxide by haemoglobin and special enzymes in the red blood cells.
• They function in the homeostatic control of the volume of the circulating blood, that of the intestinal fluids through the plasma proteins.
• They are involved in blood clotting through thrombin, fibrinogen and other Proteins factors.
• They act as the defence against infection by means of protein antibodies.
• They perform hereditary transmission by nucleo proteins of the cell nucleus.

Classification of Proteins

Proteins are classified by their:

•  Electrochemical indications (acidic, basic and neutral). Explain and give examples
•  polarity ;polar (hydrophobic), nonpolar (hydrophilic), amphiphilic. Explain these terms.
•  Function (transport, enzymes, hormones, antibodies etc)
•  chemical composition(simple and complex)
• Simple proteins(Describe the amino acid composition, the molecular mass, the charge , the structure and functions of the following:) Protamines -Albumin, Histones -Globulin

        Simple proteins

Class of Proteins	Characteristics	Examples
Albumin	Soluble in water, coagulable by heat and precipitated at high salt concentrations.	Serum albumin, egg albumin, lactal albumin (Milk), leucosin (wheat), legumelin (soyabeans).
Globulin	Insoluble in water, soluble in dilute salt solutions and precipitated by half saturated salt solutions.	Serum globulin, vitellin (egg yolk), tuberin (potato), myosinogen (muscle), legumin (peas).
Glutelin’s	Insoluble in water but soluble in dilute acids and alkalis. Mostly found in plants.	Glutenin (wheat), oryzenin (rice).
Prolamins’	Insoluble in water and absolute alcohol but soluble in 70 to 80 per cent alcohol.	Gliadin (wheat), zein (maize).
Protamine’s	Basic proteins of low molecular weight. Salmine (salmon sperm). Soluble in water, dilute acids and alkalis.	Not coagulable by heat.
Histones	Soluble in water and insoluble in very dilute ammonium hydroxide.	Globin of haemoglobin and thymus histones.
Scleroproteins	Insoluble in water, dilute acids and alkalis	Keratin (hair, HOM, nail, hoof and feathers), collagen (bone, skin), elastin (ligament).

Conjugated Proteins

Class of Proteins	Characteristics	Examples
Nucleoproteins	Composed of simple basic proteins (protamines or histones) with nucleic acids, found in nuclei. Soluble in water.	Nucleoprotamines and nucleohistones.
Lipoproteins	Combination of proteins with lipids, such as cholesterol and phospholipids etc.	Lipoproteins of egg-yolk, milk and  As fatty acids, membranes, lipoproteins of blood.
Glycoproteins	Combination of proteins with carbohydrate (mucopolysaccharides).	Mucin (saliva), ovomucoid (egg white osseomucoid (bone), tendomucoid (tendon).
Phosphoproteins	Contain phosphorus radical as a prosthetic group	Caseinogen (milk), ovovitellin (egg yolk)
Metalloproteins	Contain metal ions as their prosthetic groups. The metal ions generally are Fe, Co, Mg, Mn, Zn, Cu etc.	Siderophilin (Fe), ceruloplasmin (Cu).
Chromoproteins	Contain porphyrin (with a metal Ion) as their prosthetic group	Haemoglobin,  myoglobin, glactase
Flavoproteins	Contain riboflavin as their prosthetic Flavoproteins of liver and kidney groups.	Flavoproteins of liver and kidney

Complex Proteins

• The chemical composition and structure of complex proteins.
•  Protein component- Apoprotein
•  Nonprotein component-Prosthetic group
• Principle of classification (based on the name of the prosthetic group) and classes of complex proteins.

FOOD CONTAINING PROTEINS

• Dairy Products

• Greek Yoghurt 
• Cottage Cheese
• Regular Yoghurt
• Milk, Skim 
• Soy milk 
• Mozzarella 
• String Cheese

• Meat, Poultry, Eggs

• Chicken, skinless
• Steak 
• Turkey, roasted.
• Lamb
• Pork 
• Ham 
• Egg, 

• Seafood

• Salmon 
• Tuna
•  Shrimp 
• Lobster 
• Scallops