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प्रश्न
What are the common types of secondary structure of proteins?
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 are proteins classified on the basis of molecular shapes?
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The helical structure of protein is stabilized by:
Which of the following statement is correct:
Proteins are found to have two different types of secondary structures viz. α-helix and β-pleated sheet structure. α-helix structure of protein is stabilised by:
Dinucleotide is obtained by joining two nucleotides together by phosphodiester linkage. Between which carbon atoms of pentose sugars of nucleotides are these linkages present?
In fibrous proteins, polypeptide chains are held together by:
(i) van der Waals forces
(ii) disulphide linkage
(iii) electrostatic forces of attraction
(iv) hydrogen bonds
Which of the following are purine bases?
(i) Guanine
(ii) Adenine
(iii) Thymine
(iv) Uracil
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?
Explain the terms primary and secondary structure of proteins. What is the difference between α-helix and β-pleated sheet structure of proteins?
The main structural feature of proteins is
Explain formation of peptide linkage in protein with an example.
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:
Presence of disulphide link gives rise to which structure of protein?
The total number of negative charge in the tetrapeptide, Gly-Glu-Asp-Tyr at pH 12.5 will be ______. (Integer answers)
Proteins are polymers of ______.
β-pleated sheet structure in proteins refers to ______.
Write a classification of proteins with an example.
