Proteins in day to day life

Proteins are linear unbranched polymers made of 20 standard alpha amino acids. Proteins are used as building blocks of your body. Proteins play very important role in your day to day life. Right from your body structure to functioning, proteins are involved almost everywhere. Collagen is considered to be the most abundant protein. Collagen is a connective framework of muscles, bone, tendons, cartilage and skin. Your hair and nails contain a protein known as keratin. Keratin is known to impart strength to hair and nails. Muscles contain actin and myosin. Other kinds of proteins such as hemoglobin carry oxygen around your body. Antibodies are a class of proteins that help to fight against infections. Proteins also play an important role in laboratory detection of infections, such as presence of antibodies could help to detect various conditions, through analysis of blood and urine samples. So you can find proteins almost everywhere.

What are amino acids?

Amino acids are building blocks of proteins. They have: an amino group, a carboxyl group a hydrogen atom and a distinctive side chain. All these groups are bonded to the alpha carbon atom. There are 10 Essential amino acids such as histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine and cysteine. They are those which our body cannot synthesize in sufficient amount. So we obtain them from the diet. Non-essential amino acids can be synthesized by our body in sufficient amount. Alanine, arginine, asparagine, aspartic acid, glutamic acid, glutamine, glycine, proline, serine and tyrosine are non-essential amino acids.

Why do we need proteins?

Our body is made up of 20% proteins which make up enzymes, hormones, and components of cell membranes among many other things. Enzyme denatures and cell dies so these proteins need to be replaced. New proteins need to be re-synthesized by protein synthesis. Thus, we require continuous supply of proteins to carry out various functions in the body.

Some proteins act as enzymes:

Enzymes are biological catalysts. Some enzymes are molecular motors or motor proteins which convert energy into motion. They have ability to transduce ATP. Enzymes act as catalysts as they lower activation energy and stabilize transition state intermediates hence speed up the reaction.

Without Enzymes It Would Take More Than 50 Years To Digest One Meal!

Proteins can bind to ligands:

Molecule to which a protein binds is called as a ligand. This helps to regulate protein activity.  Binding to ligands depends upon specificity and affinity of the proteins.  A classic example is antibodies binding to antigens 

Proteins determine shape of the skeleton: Proteins play an important role in determining shape of the skeleton. Proteins such as collagen are required here.

Other functions include cell and gene reproduction, muscle build up, damage repair. Storage proteins contain energy, which can be released during metabolic processes in the organism. Egg ovalbumin and milk casein are such proteins. Almost all proteins can be digested and used as a source of energy and building material by other organisms.

Protein Synthesis for Cell and Gene Reproduction:

Cells manufacture protein by three mechanisms mainly amino acid biosynthesis, transcription of nuclear DNA into messenger RNA and finally translation by ribosomes.

Process of translation involves three main steps:

1. Binding of tRNA into ribosomes.

2. Formation of peptide bond between adjacent amino acid.

3. Movement of ribosome to next codon.

Role of translation in cell and gene reproduction:

Cytoskeletal proteins control shape and movement of cell. Mitochondrial proteins are responsible for cell respiration and ATP synthesis for energy. Histone proteins are involved in packaging of DNA. Scaffold proteins are involved in signal transduction. Proteins that result from cell’s DNA determine the defining traits of organism such as blue eyes, brown hair etc.

Damage repair:

Muscle fibres form muscle proteins and repair damaged muscle tissue. Examples: Photolyase, DNA glycosylase etc. are enzymes which can repair damaged DNA.

Malnutrition is defined as lack of nutrients in the body. About 1 million cases of malnutrition are reported in India per year. It affects people of all ages. According to World Health Organization (WHO), global burden of malnutrition are serious and lasting. There are various types of malnutrition such as protein energy malnutrition, micronutrient related malnutrition and undernutrition.