Advertisements
Advertisements
Question
What are the common types of secondary structure of proteins?
Advertisements
Solution
The secondary structure of protein refers to the shape in which a long polypeptide chain can exist. They are found to exist in two different types of structures, viz., an α-helix and a β-pleated sheet structure. These structures arise due to the regular folding of the backbone of the polypeptide chain due to hydrogen bonding between \[\begin{array}{cc}\ce{O}\\||\\\ce{-C-}\end{array}\] and –NH– groups of the peptide bond.
α-Helix is one of the most common ways in which a polypeptide chain forms all possible hydrogen bonds by twisting into a right handed screw (helix) with the –NH group of each amino acid residue hydrogen bonded to the \[\begin{array}{cc}\backslash\phantom{.....}\\\ce{C=O}\\/\phantom{......}\end{array}\] of an adjacent turn of the helix as shown in the figure.
α-Helix structure of proteins
In β-pleated sheet structure, all peptide chains are stretched out to nearly maximum extension and then laid side by side, which are held together by intermolecular hydrogen bonds. The structure resembles the pleated folds of drapery and therefore is known as a β-pleated sheet.
β-Pleated sheet structure of proteins
APPEARS IN
RELATED QUESTIONS
How are proteins classified on the basis of molecular shapes?
Discuss the optical activity of lactic acid.
What type of bonding helps in stabilising the α-helix structure of proteins?
Differentiate between the following:
Fibrous proteins and Globular proteins
Differentiate between the following :
Peptide linkage and Glycosidic linkage
Which of the following biomolecules is insoluble in water?
The protein responsible for blood clotting is ____________.
The correct statement for protein haemoglobin.
Which of the following statement is correct:
Optical rotations of some compounds along with their structures are given below which of them have D configuration.
| (I) |  |
| (II) |  |
| (III) |  |
Proteins can be classified into two types on the basis of their molecular shape i.e., fibrous proteins and globular proteins. Examples of globular proteins are:
(i) Insulin
(ii) Keratin
(iii) Albumin
(iv) Myosin
Protein found in a biological system with a unique three-dimensional structure and biological activity is called a native protein. When a protein in its native form, is subjected to a physical change like change in temperature or a chemical change like, change in pH, denaturation of protein takes place. Explain the cause.
Assertion: β-glycosidic linkage is present in maltose,
Reason: Maltose is composed of two glucose units in which C–1 of one glucose unit is linked to C–4 of another glucose unit.
Each polypeptide in a protein has amino acids linked with each other in a specific sequence. This sequence of amino acids is said to be ______.
Peptide linkage is:
Given below are two statements labelled as Assertion (A) and Reason (R).
Assertion (A): Proteins are found to have two different types of secondary structures viz alpha-helix and beta-pleated sheet structure.
Reason (R): The secondary structure of proteins is stabilized by hydrogen bonding.
Select the most appropriate answer from the options given below:
Proteins are polymers of ______.
β-pleated sheet structure in proteins refers to ______.
Write a classification of proteins with an example.
