Proteins are complex biological molecules that perform a wide variety of functions within living organisms. One common secondary structure found in proteins is the \(\alpha\)-helix. The stabilization of this structure is crucial for the protein’s functionality and is primarily due to a specific type of interaction.
The \(\alpha\)-helix is a right-handed coil structure. The key factor stabilizing this structure is the hydrogen bonds that form between the backbone atoms of the polypeptide chain.
In an \(\alpha\)-helix, the N-H group of one amino acid forms a hydrogen bond with the C=O group of an amino acid four residues earlier (i.e., the nth amino acid forms a hydrogen bond with the (n+4)th amino acid).
This regular pattern of hydrogen bonding along the backbone results in the helix structure.
Hydrogen bonds are relatively strong dipole-dipole interactions where a hydrogen atom is attracted to a highly electronegative atom like oxygen or nitrogen.
To understand why other options are not correct:
Ionic bonding: Although ionic bonds are crucial in proteins, especially those on the protein surface, they are not responsible for the \(\alpha\)-helix stabilization.
Covalent bonding: While covalent bonds (such as disulfide bridges) can stabilize the overall tertiary structure of proteins, they do not play a role in stabilizing the \(\alpha\)-helix specifically.
Van der Waals forces: Although these forces contribute to the stability of the protein structure, they are not the primary forces stabilizing the \(\alpha\)-helix.
Therefore, the correct answer is that hydrogen bonding is responsible for the stabilization of the \(\alpha\)-helix structure in proteins.
Bond Type
Relation to \(\alpha\)-Helix Stabilization
Ionic Bonding
Not involved in \(\alpha\)-helix stabilization
Hydrogen Bonding
Primary force stabilizing the \(\alpha\)-helix
Covalent Bonding
Does not stabilize \(\alpha\)-helix directly
Van der Waals Forces
Contributes to overall stability, but not primarily
An essential part of every cell in our body, protein is one of the three macronutrients which is required by our body in larger amounts. Proteins are made up of linear chains of smaller units called amino acids. Every biochemical process that takes place inside our bodies is possible because of these proteins. Proteins are 3-dimensional structures that are assembled with different amino acid sequences.
Functions of Protein
Proteins are used in many ways. Some of their functions are:
Enzymes: Most of the important chemical reactions which take place inside a cell are mostly carried out by enzymes. They also play a role in regenerating and creating DNA molecules and carrying out complex processes.
Hormonal Regulation: Proteins create various types of hormones that help in balancing the components of the body. For example, hormones like insulin help in regulating blood sugar and secretin. The formation of digestive juices essential for the whole digestion process is also possible because of hormones.
Protection: Being the main constituent of antibodies, proteins protect our body against antigens and pathogens thus preventing infections.
Energy: Proteins are one the most essential sources of energy required for our body movements. The right amount of proteins should be consumed so that they can be turned into energy.
Structural functions: Proteins are the building blocks of the body. They are required for the growth, development, healing, and repair of tissues. Proteins are essential in order to strengthen various structures like hair, skin, and muscles. It is also present in the outer membrane of all cells in the human body.
Classification of Protein
Proteins are classified on the basis of:
Shape
Constitution
Nature of Molecules
Protein Structure
A protein molecule is made from a long chain of amino acids, each linked to its neighbor through a covalent peptide bond. The structure of proteins are divided into four types:
