Elementary Idea of Tertiary Structure of Proteins

Tertiary Structure of Proteins: The tertiary structure is the specific three-dimensional arrangement of all the amino acids in a single polypeptide chain and is the next level up from the secondary structure. This structure is often conformational, native, and active, with many noncovalent connections holding it together.

Introduction To Proteins

Protein structures are generated by the condensation of amino acids, which results in the formation of peptide bonds. The sequence of amino acids in the protein’s primary structure. The secondary structure is determined by the dihedral angles of the peptide bonds, whereas the tertiary structure is determined by the folding of protein chains in space. When folded polypeptide molecules bind to complex functional proteins, they produce a quaternary structure.

In the great majority of situations, proteins fold into various three-dimensional structures. The natural conformation of a protein is the shape into which it folds spontaneously. Many proteins can fold on their own due to the chemical characteristics of their amino acids, whilst others require the assistance of molecular chaperones to fold in their native forms.

The tertiary structure is the specific three-dimensional arrangement of all the amino acids in a single polypeptide chain and is the next level up from the secondary structure. This structure is often conformational, native, and active, with many noncovalent connections holding it together.

The tertiary structure is when polypeptide chains become functional. At this level, each protein has a distinct three-dimensional form and functional groups on its outer surface that allow it to interact with other molecules and provide it with its distinct function. The arrangement is achieved with the assistance of chaperones, which move the protein chain around, bringing various groups on the chain closer together to aid in bond formation. These interacting amino acids are frequently located widely apart on the chain.

Tertiary Structure of Protein

• This structure results from the subsequent folding of the protein’s secondary structure.
• This structure is held together by H-bonds, electrostatic forces, disulfide connections, and Vander Waals forces.
• The tertiary structure of proteins represents the overall folding of the polypeptide chains, as well as further folding of the secondary structure.
• It produces two primary molecular shapes: fibrous and globular.
• Hydrogen bonds, disulfide connections, van der Waals forces, and electrostatic forces of attraction are the primary factors that stabilize the secondary and tertiary structures of proteins.
• For example, amide hydrogen atoms can establish H-bonds with neighbouring carbonyl oxygens; as a result of these tiny local structures, an alpha helix or beta sheet can zip up.

Also Read: Elementary Idea of Quaternary Structure of Proteins

Tertiary Structure Interactions

The following are the major interactions that build up proteins’ tertiary structures. They direct the bending and twisting that allows the protein molecule to reach stability. We can see covalent interactions, in which pairs of electrons are exchanged between atoms, or non-covalent interactions, in which pairs of electrons are not shared between atoms.

• Hydrophobic Interactions

These non-covalent bonds are the most important element in the creation of the tertiary structure. When we put hydrophobic (anti-water) molecules in water, they congregate and create enormous pieces of hydrophobic molecules. Because certain R-groups are hydrophilic (love water) and others are hydrophobic, all amino acids with hydrophilic side chains, such as isoleucine, will be located on the protein’s surface, whereas amino acids with hydrophobic side chains, such as alanine, will collect together at the protein’s core. As a result, most proteins that develop in water have a hydrophobic core and a hydrophilic surface. This is critical in defining how the tertiary structure will be laid out.

• Ionic Bonding

Some amino acids have positively or negatively charged side chains. If a positively charged amino acid comes close enough to a negatively charged amino acid, it can form a connection that serves to stabilize the protein molecule.

• Bonds of Hydrogen

These bonds may be seen between water molecules in the solution and the hydrophilic amino acid side chains on the molecule’s surface. Hydrogen bonds form between polar side chains and aid in the stabilization of the tertiary structure.

• Disulfide Bridges

These are very strong covalent interactions formed between cysteine residues that are near in space. The sulphur groups on the various cysteine residues create bonds.

Types of Tertiary Structures

• Globular Proteins

The majority of proteins belong to this group. Globular proteins have a tight ball shape with hydrophobic amino acids in the interior and hydrophilic amino acids on the surface, resulting in a molecule that is soluble in water. Many globular proteins contain domains, which are locally folded sections of the tertiary structure that range in size from 50 to 350 amino acids. If the proteins have comparable activities, one domain can be found in numerous proteins, and a protein with multiple functions can have multiple domains, each performing a specialized role. Enzymes are an example of globular proteins found in our cells.

Examples: Haemoglobin, myoglobin, insulin, enzymes

• Fibrous Proteins

Fibrous proteins are composed of fibres, which are typically repeating sequences of amino acids, resulting in a highly organized, extended structure. They include cartilage, which offers structural support, and are water-insoluble.

Examples: Keratin, collagen, elastin, fibrin

FAQs

What are the four phases of protein structure?

Protein structure has four levels. The four phases of protein structure are the primary, secondary, tertiary, and quaternary levels.

How do proteins form?

When amino acids are linked together by peptide bonds, they produce a polypeptide, which is another term for protein. The polypeptide subsequently folds into a specific shape depending on the interactions (strained lines) between its amino acid side chains.

Is DNA a type of protein?

DNA is frequently associated with histone proteins in the nucleus, but DNA is not a protein. No, DNA is a nucleic acid composed of purine and pyrimidine-based phosphate and sugar groups, whereas proteins are huge molecules composed of one or more lengthy amino acid chains.

What is the distinction between fibrous and globular proteins?

Fibrous proteins are structural in nature, which means they help keep cells in form by acting as scaffolding or a framework. Globular proteins, on the other hand, are functional, which implies they perform a specific biological role in the body.