I got this problem wrong and need the correct answer with explanation. 30. Answe

Question

I got this problem wrong and need the correct answer with explanation. 30. Answer the following questions about the protein human serum albumin. a) In human serum albumin, there are several -helical segments. Is this an example o tertiary, because tim are severen-he1i b) In human serum albumin, the first ten amino acid residues are Met-Lys-Trp-Val-Thr- is e protein sfrecture, beca primary, secondary, tertiary, or quaternary protein structure? (2 points) Ile-Ser-Leu-Leu, in that order. Is this an example of primary, secondary, tertiary, or quaternary protein structure? (2 points) xampfe of primary there ir amino acid squence, ani not he1ic

Explanation / Answer

Ans. #30. A. Secondary structures.

The alpha-helices are example of secondary structure. The localized folding of small segments ( 3- 30 residues) of a polypeptide into ordered geometrical units is called secondary structure. A single polypeptide may have several of these localized geometric units, thus are sometimes also called the ‘repeating unit/ structure’. Secondary structures are stabilized purely by non-covalent interactions like van der Waal’s forces, hydrophobic interactions and H-bonds. Example- -helix and - sheet.

Note: You answered correctly with respect to the albumin protein – it’s a tertiary structure. However, it seems that the term “it” in the question specifies the “a-helices” LIKE “it” means “amino acid sequence” in part b.

#b. Primary structure: Linear polymer of amino acids of a polypeptide chain is called its primary structure. It gives the amino acid sequence of the peptide chain.

           

# Tertiary Structure: The overall 3D conformation of a polypeptide chain is called its tertiary structure. Tertiary structure may also be stabilized by intra-peptide chain (intramolecular) disulfide bridge (-S-S-) between cysteine residues brought together in close proximity during folding. The non-covalent interactions includes H-bonds, ionic interactions, hydrophobic interactions, etc. among the residues of the same polypeptide chain.

Quaternary Structure: The quaternary structure of protein is an association of two or more polypeptides into a distinct structural/functional unit. Two polypeptides in quaternary structure may be held together by inter-peptide chain (intermolecular) disulfide bonds and/or non-covalent interactions. The non-covalent interactions includes H-bonds, ionic interactions, hydrophobic interactions, etc. among the residues of the same polypeptide chain, and among residues of two or more polypeptides.  

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