. er is a Ramachandran plot of actual vs. data obtained from the crystal structu
ID: 3476036 • Letter: #
Question
. er is a Ramachandran plot of actual vs. data obtained from the crystal structure or a po protein. Which of the following most likely describes this protein's most predominant structure? secondary A. Region A: --140"; y_ + 130", many Ala residues; . helix Region B: -60"; --47", many Pro residues; -helix C. Region C: 0"; y, = +47"; many Gly residues; random D. Region A:-140"; -+ 130, many Val residues; - l E. Region B:-60.. -47; many Ala residues; -helix coil sheet 1. Circular dichroism measurements have shown that the peptide backbone of poly--lysine (KKKKKKK) 0. adopts a random coil conformation at pH 7.0, but becomes -helical as the pH is raised above 1 This observation is known as the 'helix-coil' transition. Predict the helix-coll transition of the poly-L- glutamate (EEEEEEE) A. B. C. Helix below pH 4.4 and coil above pH 4.4 Coil below pH 4.4 and helix above pH 4.4 Helix above pH 10 and coil below pH 10.2 Helix below pH 10 and coil above pH 10.2 Will not undergo a helix-coil transition [3 points] What is the approximate length difference of a 22-kDa single-stranded -helical protein 12. / segment vs. a 22-kDa single-stranded -strand protein segment? Assume a mean residue mass of 110 Da. Show work.Explanation / Answer
The first question details are cut off in the figure. So am answering the second.
Since lysine is a basic amino acid and has a pI value of 9.74, it changes from coil to helix after the pI value is crossed. Since glutamate is an acidic amino acid with a pI value of 3.22, it indicates that it will be at a helix conformation below the pH of 4. And turn into coil above pH 4.
Hence, the option A is correct.
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