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प्रश्न
What are the common types of secondary structure of proteins?
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उत्तर
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
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संबंधित प्रश्न
How is tripeptide formed?
Define the following as related to proteins:
Peptide linkage
What type of bonding helps in stabilising the α-helix structure of proteins?
Differentiate between the following:
Fibrous proteins and Globular proteins
Write one difference between α-helix and β-pleated structures of proteins.
The protein responsible for blood clotting is ____________.
The helical structure of protein is stabilized by:
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
Which moieties of nucleosides are involved in the formation of phosphodiester linkages present in dinucleotides? What does the word diester in the name of linkage indicate? Which acid is involved in the formation of this linkage?
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 ______.
Explain formation of peptide linkage in protein with an example.
Out of the following, which type of interaction is responsible for the stabilisation of the α-helix structure of proteins?
An α-helix is a structural feature of ______.
Proteins are polymers of ______.
Write a classification of proteins with an example.
Statement I: A protein is imagined as a line, the left end represented by first amino acid (C-terminal) and the right end represented by last amino acid (Nterminal).
Statement II: Adult human haemoglobin, consists of 4 subunits (two subunits of a type and two subunits β type.)
In the light of the above statements, choose the correct answer from the options given below:
