Protein is a complicated molecule that is found in almost all living things. Proteins are nutrient-dense and play an important role in the chemical reactions that keep life running. In the early nineteenth century, scientists recognised the importance of proteins, particularly Swedish chemist Jöns Jacob Berzelius, who coined the term protein in 1838, derived from the Greek prteios, which means “first position.” Proteins are species-specific as well as organ-specific; for example, muscle proteins differ from brain and liver proteins within the same organism. A protein molecule is significantly larger than a sugar or salt molecule, and it is made up of numerous amino acids linked in long chains, similar to beads on a string.
Structure of Protein
Proteins are made up of a polymeric chain of amino acids. A protein’s structure is primarily made up of long chains of amino acids. Proteins have specific features according to the structure and location of amino acids. An amino functional group (-NH2) and a carboxyl group make up amino acids (-COOH).
Polypeptide chains are made up of amino acids bonded together. To produce a protein, one or more of these chains fold in distinct ways. Amino acids are substituted methane, with hydrogen, amino groups, and carboxyl groups occupying the first three valences of the – carbon, and a variable R- group filling the fourth valency. A tiny number of amino acids, each with its side chain, make up proteins. The chemistry of amino acid side chains varies. The bulk of amino acids has nonpolar side chains.
In general, there are two types of protein molecules: fibrous proteins and globular proteins. Fibrous proteins are insoluble because they are stretched. The body contains globular proteins that are soluble and compact. Primary, secondary, tertiary, and quaternary protein structures can all be found in fibrous and globular proteins.
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Primary: It is made up of a specific sequence of amino acids. Information contained in genes detects the order in which amino acids are linked together.
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Secondary: It is a three-dimensional representation of a protein’s local segment. They are produced by hydrogen bonding between atoms along the polypeptide chain’s backbone.
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Tertiary: R-groups determine the tertiary level. It’s a protein’s three-dimensional form. A quaternary structure is formed by the folding of a large number of tertiary structures.
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Quaternary: The arrangement of numerous folded protein subunits in a multi-subunit complex is known as a quaternary structure.
Functions of proteins
Proteins have many functions some of which are listed below:-
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Enzymes: Enzymes are the proteins that carry out all of the chemical events that occur within a cell. They also assist in the regeneration and creation of DNA molecules, as well as the execution of complex procedures.
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Hormones: Proteins are involved in the production of a variety of hormones that aid in the balancing of the body’s components. Hormones like insulin, which helps regulate blood sugar, and secretin, for example. It aids digestion and the generation of digestive fluids as well.
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Antibody: An immunoglobulin is a type of antibody. It’s a type of protein that the immune system uses to mend and heal the body after it’s been infected by bacteria. They frequently collaborate with other immune cells to recognise and segregate antigens, preventing them from multiplying until they are destroyed by white blood cells.
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Energy: Proteins are the primary source of energy that aids in our body’s movement. To turn protein into energy, the proper amount of protein is required. Protein is needed to make fat and becomes a part of fat cells when taken in excess amounts.
Protein hormones
Protein hormones include insulin, glucagon, thyrocalcitonin, pituitary hormones, and hypothalamus hormones. Polypeptide hormones are another name for them. This is the peptide hormones list. We’ll learn more about them further on.
INSULIN: The pancreas’ beta cells produce human insulin. In nature, the insulin hormone is a peptide or protein. It aids in the maintenance of glucose homeostasis in the body. It acts by interacting with various bodily cells such as hepatocytes, adipocytes, and muscle cells. These cells can use up the glucose in the blood as a result of its action, which helps to lower blood sugar levels in the body. When the level of glucose in the body rises, the insulin hormone is released, which aids in the following:
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Glucose is used by bodily cells for respiration.
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Amino acids are taken in by cells and hence assist in protein production.
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Fat synthesis by adipose tissue.
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The liver and muscles are responsible for glucose absorption.
When the insulin hormone isn’t released in the right amounts, the body’s ability to function properly can be jeopardised. Diabetes mellitus is one of the diseases caused by inadequate insulin levels. Because the body produces no or very little insulin, the glucose is not taken up by the cells and remains in the bloodstream. Almost all of the body’s organs, particularly the eye and brain, are affected.
GLUCAGON: One of the peptide hormones is glucagon. The pancreas releases this hormone as well. The pancreas’ alpha cells aid in the release of the glucagon hormone. A-cells are another name for these cells. The glucagon hormone has the opposite effect as insulin. On the one hand, while insulin lowers blood glucose levels, the glucagon hormone helps to raise blood glucose levels. This hormone operates on the liver cells, assisting them in the release of glucose by breaking down glycogen stored in the cells. The activation of the gluconeogenesis pathway is caused by this hormone. This suggests that this mechanism results in increased glucose production. It also aids in the liver’s conversion of other nutrients, such as amino acids, to glucose.
THYROCALCITONIN:
The thyroid gland is the source of this hormone. Thyroid hormones have the following functions: –
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The thyroid hormones regulate protein, carbohydrate, and fat metabolism. This, in turn, aids in the regulation of the body’s growth and development.
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These hormones aid in the process of erythropoiesis, which is the creation of red blood cells.
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They also aid in regulating the body’s water and electrolyte balance.
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Thyroid hormones are responsible for the physical and mental development of all body tissues.
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Thyroid hormones also regulate the body’s resting metabolic rate. More heat energy is released when the metabolic rate of the organism is increased.
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Thyroid hormone is also involved in the body’s tissue differentiation process.
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Thyroid hormones influence the formation of tadpole tails as well.
CONCLUSION
Amino acid chains fold into different three-dimensional shapes to form proteins. The structure of protein molecules is stabilised by bonding, and the folded shapes of proteins are well-suited to their functions. Proteins are large biomolecules and macromolecules made up of one or more long amino acid chains. Proteins play a range of activities in organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and animals, and transporting resources. Proteins differ primarily in their amino acid sequence, which is determined by the nucleotide sequence of their genes and usually results in the protein folding into a certain 3D structure that determines its activity.