For each polypeptide sequence listed, choose from the options given below to indicate which secondary structure the sequence is most likely to form upon folding. The nonpolar amino acids are italicized
A. Leu-Gly-Val-Leu-Ser-Leu-Phe-Ser-Gly-Leu-Met-Trp-Phe-Phe-Trp-Ile
B. Leu-Leu-Gln-Ser-Ile-Ala-Ser-Val-Leu-Gln-Ser-Leu-Leu-Cys-Ala-Ile
C. Thr-Leu-Asn-Ile-Ser-Phe-Gln-Met-Glu-Leu-Asp-Val-Ser-Ile-Arg-Trp
amphipathic ? helix hydrophilic ? sheet
amphipathic ? sheet hydrophobic ? helix
hydrophilic ? helix
A. Hydrophobic ? helix. Nearly all of the amino acid side chains in this sequence are nonpolar or hydrophobic, which favors the only hydrophobic option given in the list.
B. Amphipathic ? helix. In an ideal ? helix, there are 3.6 residues per complete turn. Thus, an amphipathic helix with one hydrophobic side and one hydrophilic side will have, minimally, nonpolar side chains (N) repeating every third then next fourth amino acid: NxxNxxxNxxNxxxN. Polar side chains (P) will have the same pattern but shifted relative to the nonpolar side chains; for example, xxPxxxPxxPxxxPxxP.
C. Amphipathic ? sheet. Because of the zigzag-like structure of a ? sheet, a sequence with alternating nonpolar and polar side chains may form an amphipathic ? sheet that is hydrophobic on one side and hydrophilic on the other.
You might also like to view...
The coding regions of a gene are known as ________.
Fill in the blank(s) with the appropriate word(s).
The leading edge of a hypha is in the __________ stage of cell division
a. anaphase b. interphase c. metaphase d. prophase
During stress, ACTH is produced by the _______ and acts on target cells in the ______
a. hypothalamus; adrenals b. hypothalamus; pituitary c. pituitary; hypothalamus d. pituitary; adrenals e. adrenals; hypothalamus
In the human male, sperm are produced in the ____
a. bulbourethral glands b. prostate c. seminiferous tubules d. vas deferens e. epididymis