Proteins






Proteins are essential elements that, like water,  are the basic building materials responsible for the development and growth of muscles , bones, ligaments and tissues. In addition, proper digestion and preservation of the immune system are also a function of protein. Therefore, it is extremely important to introduce them in the correct amounts into the body and in the right way.


10 foods that are the best sources of protein


1. White chicken meat


 White meat contains a large amount of protein. It is healthier than red meat due to its high content of lean proteins and low content of cholesterol and fat . 100 g of chicken meat contains as much as 32 g of protein. Chicken is best eaten boiled, baked or grilled.


2. Fish


Fatty fish such as salmon, tuna, trout and sardines are good sources of protein. Omega - 3 and omega - 6 fatty acids  are, in addition to protein, the main ingredient of this food. Heart diseases in humans are often caused by insufficient intake of omega acids . Protein content in 100 g of some fish: tuna 24 g, salmon 20 g, halibut 46 g.



3. Beans and legumes


All types of beans (white, red, chickpeas, soybeans) have a fairly high protein content. Dietary fiber and as many as 8 essential amino acids are also found in the composition of most legumes. 100 g of beans or soybeans contain up to 12 g of protein.


4. Eggs


Eggs are an excellent source of protein, especially egg whites, which have very low cholesterol and high protein content. Egg whites are also very low in fat and provide you with essential amino acids. 100 g of egg white contains 26 g of protein.


 5. Nuts


Nut products such as almonds, peanuts, cashews and Brazil nuts belong to high-protein foods . Nuts are a source of amino and omega-3 fatty acids that help build muscle and prevent dry skin . The only downside to nuts is that they have a high fat content, so they should be consumed in moderation . Protein content in 100 g of nuts: walnuts 33 g, almonds 21 g, peanuts 8 g, sunflower seeds 6 g, flax seeds 5 g.


6. Dairy products


Milk, yogurt, cheese and cream are important sources of protein. Essential nutrients such as calcium , essential minerals and vitamins can best be obtained through these foods. Skimmed milk and low-fat dairy products are a healthier choice, especially for people who are overweight . Protein content in 100 g of some types of dairy products: milk 6 g, yogurt 6 g, Parmesan cheese 10 g, low-fat Swiss cheese 8 g.


7. Cauliflower, Broccoli and Broccoli


Cauliflower, in addition to its significant protein content, contains fiber and vitamin K , which has an anti-inflammatory effect on many body functions. 100 grams of cauliflower contains 3 grams of protein. Broccoli and Brussels sprouts have a low fat content, while vitamin A , vitamin B , vitamin C, iron and dietary fiber are the dominant ingredients of this food. 100 grams of broccoli contains 2.8 grams of protein, while 100 grams of sprouts contain 4 grams of protein.


8. Sweet corn


This food is very rich in proteins and B complex vitamins. folic acid and pantothenic acid are also essential ingredients of this cereal. 100 g of sweet corn contains 4 g of protein.



9. Soy milk


Soy milk is a good alternative for vegetarians to get their daily protein intake. 100 g of soy milk contains 4 grams of protein.


10. Bananas


Bananas belong to the healthiest type of fruit. 100 grams of bananas contain 4 g of protein, which is why this food is recommended for breakfast. Bananas are rich in potassium and are a good choice for people suffering from constipation.








PROTEIN PRODUCTS FOR A BEAUTIFUL FIGURE

Are you exercising regularly but not getting the results you want? High protein foods will help you get leaner and stronger.
Proteins are a key group of nutrients that are mainly involved in the structure of the muscular skeleton. As a result of digestion, such substances break down into essential amino acids, enrich the body with additional energy, and also normalize metabolic processes. If you eliminate protein foods from your diet, chronic fatigue will begin to accompany you day after day.


PROTEIN BALANCE: WHAT FOODS WILL LEAD YOU TO THE GOAL


According to nutritionists, the average daily intake of protein is 80–100 g per 1 kg of body weight. Experts believe that this is the optimal dose for the normal functioning of internal organs and tissues. However, protein foods are heterogeneous. Conventionally, it is divided into 2 classes: one brings the least benefit to the body, the other the most.
The first class includes semi-finished products, sausages, salted and smoked products, canned food, etc. These products undergo technological processing and are prepared from low grades of meat. During the production process, they change their properties, lose most of the vitamins and minerals, become fatty, so they are worse synthesized by the body and contribute to the emergence of toxins in it.
In order not to put your health at risk, replenish your protein balance with second-class products - natural protein of animal and vegetable origin. Among such products are animal and poultry meat, seafood, dairy and sour-milk products, eggs, nuts, cereals and legumes.


LIST OF PROTEIN FOODS GOOD FOR HEALTH


Lean meats. Chicken, turkey, rabbit, as well as beef and veal fillets are some of the most common sources of protein. 100 g of meat contains an average of 20-25% protein and only 1-3% fat, so it is easily digestible and provides the body with essential amino acids, potassium, phosphorus, magnesium and other vitamins and minerals.

Seafood. 

Fish, squid, crabs and most other representatives of the water element are characterized by a high content of high-quality protein and the essential amino acid methionine. In 100 g of seafood - an average of 18-20% protein and 3-7% fat. At the same time, the digestibility of fish proteins is 10–15% higher than that of meat proteins.

Eggs. 

The fastest digesting protein among the other 7 protein foods. It consists of the optimal number of amino acids for a person, phosphorus, sulfur, iron, zinc and fats, which normalize cholesterol metabolism in the body. In addition, eggs are rich in vitamins D and group B.

Dairy and dairy products

 Milk, sour cream, cottage cheese and butter have a high protein density and are among the essential foods for muscle growth. They are rich in nutrients - they have a positive effect on the immune system and the functioning of the organs of the gastrointestinal tract.

Nuts.

  The leader of protein products of plant origin in terms of the amount of protein in the composition. 100 g of nuts contains an average of 20–25% of proteins, as well as a considerable number of other nutrients, micro and macro elements.

Cereals. 

Wheat, rye, corn, rice and oats have a balanced amino acid composition. 100 g of cereals contain 8–12% vegetable protein, which improves skin condition and removes toxins.

Legumes. 

Peas, beans, lentils and beans are the main representatives of legumes, which contain 5-10% protein per 100 g of the product. It is recommended to take them together with cereals in order to get all 8 essential amino acids in total.

The protein nutrition system does not exclude the intake of carbohydrates and fats. Your diet should take into account the physiological characteristics of your body and be balanced. However, people who take care of their health and exercise regularly should eat plant and animal protein products and combine them harmoniously in order to improve their fitness performance.







Structure 

  A protein refers to a polypeptide chain that is folded into a unique three-dimensional structure .The structure in which a protein is folded in its natural state is determined by the sequence that make up this polypeptide of the protein . Biochemists divide the structure of proteins into four stages.

Primary structure  

Amino acid sequence The structure of a single protein can be changed by the environment and other interacting molecules. This structural modification plays a very important role in the biological functions of proteins such as catalysis , binding to other molecules, and mechanical movement. The primary structure of these linear proteins consists of covalent peptide bonds , which are formed when the protein is synthesized by ribosomes . The secondary, tertiary, and quaternary structures of proteins are maintained by the bonds between the backbone chain and side chain structures that make up the protein. These bonds are divided into non- covalent bonds such as hydrogen bonds , hydrophobic bonds , and ionic bonds , and covalent bonds such as disulfide bonds .

Secondary structure 

 The secondary structure of a protein is formed by the backbone chain. A hydrogen bond is formed between the oxygen atom of the carbonyl group and the hydrogen atom of the amine group of all amino acids in the skeleton, resulting in a thermodynamically stable state (the state with the lowest free energy). At this time, the reason that the secondary structure of the protein mainly takes the shape of an α-helix or a β-sheet is that between two amino acids located right next to each other on the polypeptide side chain and the atoms of the skeleton This is because the stable shape that minimizes the pushing force forms the shape of the alpha helix or beta plane. This indicates that the most stable secondary structure forms the shape of an alpha helix or a beta plane due to the primary folding by the hydrogen bond of the skeleton . The Ramachandran plot shows this trend more clearly.

Tertiary structure 

Tertiary structure of a protein is determined by the hydrophobic bonding of the side chains that make up the protein. Although disulfide bonds and hydrogen bonds make the tertiary structure more stable, the most important force that determines the tertiary structure is the hydrophobic bond. 

Quaternary structure 

In the quaternary structure of a protein, several polypeptides are gathered by hydrophobic bonds to function as a single protein, and may not exist when a single polypeptide plays a unique role as a protein. Like the tertiary structure, it becomes more stable by disulfide bonds, hydrogen bonds, and ionic bonds.

The process by which an amino acid sequence forms a complex tertiary structure is called protein folding . Usually, the unique tertiary structure of each protein is the lowest free energy that the amino acid sequence can have. Also, a state with low free energy is an active state that performs a biological function. However, proteins can exist in higher energy states. Only because of its high energy, the amount of protein that exists in a high energy state in nature is very small. The energy required to reach a state in which the structure of a protein is completely unraveled (the state in which the secondary, tertiary, and quaternary structures are all lost) in the most stable state determines the thermodynamic stability of a protein.

Both ends of the amino acid sequence are called the N-terminus and the C-terminus . It is named because one end of the protein has an amino group (-NH₂) and the other has a carboxyl group (-COOH).