Protein : What is protein, structure, digestion, role in the body and healthy sources of protein.

This post include everything you need to about Protein : What is protein, structure, digestion, role in the body and healthy sources of protein.

Let's first discuss what is protein?
Proteins are essential nutrients for human body.
They are the one of the building blocks of body tissue, and can also serve as a fuel source. As fuel, proteins contain 4 kcal per gram, just like carbohydrates and unlike lipids, which contain 9 kcal per gram.
These are the polymer chain made of amino acids linked together by peptide bonds.
It contains C, H, O, N.

Protein makes up the building blocks of organs, muscles, skin hormones.
A diet high in protein also lowers blood pressure and fight diabetes and more.

Amino acids are found in animal sources such as meats, milk, fish and eggs.  As well as in plant sources such as whole grains, nuts, seeds, pulses, legumes, soy and fruits.

Essential amino acids cannot be made by the body, and must be supplied by food. Non-essential amino acids are made by the body from essential amino acids or in the normal breakdown of proteins.

Conditional amino acids are usually not essential except in time of illness, stress or for someone challenged with a lifelong medical condition.
 Protein source-
Sources of complete protein include eggs, milk, meat, fish, and poultry. Eggs provide the optimal mixture of essential amino acids among all food sources.  Reliance on animal sources for dietary protein accounts for the relatively high cholesterol and saturated fatty acid intake in the major developed nations. High-quality protein foods come from animal sources. Vegetables (lentils, dried beans and peas, nuts, and cereals) remain incomplete in one or more essential amino acids; thus, their proteins have a lower biologic value. Eating a variety of grains, fruits, and vegetables supplies all of the essential amino acids.

This post tell you  everything about Protein : What is protein, structure, digestion, role in the body and healthy sources of protein.

 Structure of protein

 Protein structure is the bi molecular structure of a protein molecule.
Each protein is a polymer specifically a polypeptide - that is a sequence formed from 20 possible L-alpha-amino acids.
To be able to perform their biological function, proteins fold into one or more specific spatial Conformations, driven by a number of no covalent interactions such as hydrogen bonding, ionic interactions and hydrophobic packing.

There are four distinct levels of protein structure:
Primary structure
The primary structure refers to amino acid linear sequence of the polypeptide chain. The primary structure is held together by covalent or peptide bonds.
Primary structure

The primary structure refers to amino acid linear sequence of the polypeptide chain. The primary structure is held together by covalent or peptide bonds.

Secondary structure

It refers to highly regular local sub-structures. Two main types of secondary structure:

the alpha helix and the beta strand or beta sheets.Tertiary structure It refers to three-dimensional structure of a single protein molecule. The alpha-helices and beta sheets are folded into a compact globule.

 Quaternary structure

It is the three-dimensional structure of a multi sub unit protein and how the sub units fit together. It is a complex of two or more polypeptides (i.e. multiple sub units) which are called multimers.

It refers to highly regular local sub-structures. Two main types of secondary structure:
the alpha helix and the beta strand or beta sheets.

Tertiary structure

 It refers to three-dimensional structure of a single protein molecule. The alpha-helices and beta sheets are folded into a compact globule.
 Quaternary structure
It is the three-dimensional structure of a multi sub unit protein and how the sub units fit together. It is a complex of two or more polypeptides (i.e. multiple sub units) which are called multimers.

 Sources of proteins

 Animal sources: - Meat, eggs and fish are rich sources.
Plant Sources: - Whole grains and cereals are another source of proteins.
 Another vegetarian source of proteins include legumes (pulses), nuts, seeds and kidney beans, almonds, fruits, soybeans, lentils, seeds, and cashews, walnuts, sesame, sunflower seeds etc.
Healthy people eating a balanced diet rarely need protein supplements. Protein powders such casein, whey, egg, rice and soy are processed and manufacture source of protein.
These protein powders may provide an additional source of protein for bodybuilders and other athletes.

 Digestion of Proteins

 Enzymes responsible for digestion of protein are called proteolytic enzymes.
Protein digestion takes place in two different phases:

·         In the stomach.

·         In the small intestine.

Both of these phases of digestion are based on several types of enzymes that are called proteinases and proteases.
Digestion of protein in the stomach:

      Pepsinogen        -----------------HCL---------------> pepsin (enzyme)

• The process that takes place when proteins are disintegrated by the enzymes is called hydrolysis.
•  Hydrochloric acid is used for breaking the bonds between the proteins.
• Next, the proteins are disintegrated into amino acids.
• Pepsin , the gastric enzyme is capable of digesting collagen, a fibrous protein  that is one of the main constituents of connective in animals.

       Digestion of Proteins in small intestine

·          Most acids of peptides longer than four amino are not absorbed in stomach.

·         Trypsin and chymotrypsin are pancreatic protease enzymes secreted by the pancreas.

·          From the stomach, protein digestion carries on in the duodenum, i.e. the first segment of the small intestine.

·         Hydrolysis involves the insertion of a water molecule between two amino acids, which forces the bond between them to break.
    

Absorption of protein:

The protein are absorbed in the form of amino acids from small intestine. The levo amino acids are actively absorbed by means of sodium co-transport, the dextrose amino acids are absorbed by means of facilitated diffusion.
The absorption of amino acids is faster in duodenum and jejunum and slower in ileum.

Functions of Protein/Role of protein in the body:

image from pixabay.

Protein has a range of essential functions in the body, including the following:

1. Protein required for building and repair of body tissues (including muscle).
2. Enzymes, hormones, and many immune molecules are proteins.
3.  Essential body processes such as water balancing, nutrient transport, and muscle Contractions require protein to function.
4. It is a source of energy.
5. It helps keep skin, hair, and nails healthy.
6.  Like most other essential nutrients , protein is crucial for overall good health.
7.   Digestion- Digestion is carried out by the digestive enzymes which are basically proteinaceous in nature.
8. Movement-Myosin is a protein found in the muscles which enables the contraction of muscles making movement possible.
9.  Structure and support- Keratin is the structural protein which makes our hair, nails and horns in animals.
10. Cellular communication- Cells communicate with other cells and the external environment via receptors present on surface of the cells.These receptors are made of protein.
11.    Acts as a messenger- These proteins functions as the chemical messengers , which help in the communication between the cells , tissue  and organs.

Protein deficiency

Protein deficiency and malnutrition can lead to variety of ailments including:

Ø  Mental retardation and

Ø  Kwashiorkor.

Ø  Symptoms of kwashiorkor include apathy, diarrhea, inactivity, failure to grow, flaky skin, fatty liver, and enema of the belly and legs.

 Healthy Sources of Protein:-

 Here is list of delicious foods that are high in protein:-
Seafood:-
Seafood is an excellent source of source of protein because it is low in fat. Fish such as salmon is little higher in fat, but it is the heart healthy. It contains omega-3 fatty acids. Tuna is also very high in various nutrients.

Peanuts:-
Peanuts are incredibly delicious. They are high in protein, fiber, magnesium. Peanut butter is also high in protein. Just make sure not to eat too much. Moderation is key.

Lentils:-
Lentils are type of legumes. They are high in fiber, magnesium, potassium, iron, folate, copper, manganese and various other nutrients. Lentils are among the best sources of plant based protein and excellent source of food for vegetarians.

Milk:-

Milk is highly nutritious, but the problem is that huge % of world population is intolerance to milk especially African people. However, if you can tolerate milk and enjoy drinking it, then milk can be excellent source of high quality protein. It is highly in calcium and phosphorus.

Broccoli:-
Broccoli is a healthy vegetable, loaded with vitamin C, vitamin K, fiber and potassium. Broccoli is high in various bio active nutrients. It is very high in protein compared to other vegetables.

Eggs:-

 Egg whites are among the healthiest and most nutritious foods on the planet. They are loaded with vitamins, minerals and healthy fats. Egg whites are almost pure protein.

SUMMARY

Proteins differ chemically from lipids and carbohydrates because they contain nitrogen in addition to sulfur, phosphorus, and iron. All animal and plant cells contain protein. Complete proteins contain all the essential amino acids; Incomplete proteins represent the others.
 Examples of higher quality( complete proteins include animal proteins in eggs, milk, cheese, meat, fish, and poultry. Physically active people and competitive athletes can usually obtain the required nutrients predominantly from a broad array of plant sources.
For adults, the protein RDA equals 1 g per kg of body mass.  The amount of protein required in person’s diet is determined by: overall energy intake, the body’s need for nitrogen and essentials amino acids, body weight and composition, physical level exercise as well as the presence of illness or injury. Soprotein play a very important role in our body.