A schematic diagram of the helical structure of cytochrome b562 is reproduced below. This protein belongs to the family of -proteins that have a four-helix bundle. Number the helices 1 – 4 according to their N  C direction. Indicate relative orientations of the macrodipoles of helices 1 – 4 adjacent to the diagram of cytochrome b562. Remember that according to the definition of a dipole that the arrow points towards the positive end.

3) You are working on a protein with the following sequence in an area of interest.    -Asp-Leu-Leu-Gln-Glu-Glu-Asp-Glu-Ser-Arg  a. The current structure, solved at pH 7.4, of this segment has an alpha helix that is disrupted a er the Gln. Why might the alpha helix stop at this residue?     b. This protein is involved in Lysosomes in vivo. The secondary structure of this region is expected to change into a complete alpha helix. Why might this change into a complete helix? ( Hint: Lysosomes are acidic!)

α-Keratin is an intermediate filament with a basic structural unit of two a helices in a coiled coil. Each helix has a seven-residue repeating unit (heptad repeat). A representation of the a helices of a coiled coil dimer is shown. Each letter represents a different amino acid residue. f g d e Review the table of amino acids. a d g f Identify the three true statements about the structure of keratin. ☐ The a helix of the coiled coil is wound less tightly than predicted for an α helix. ☐ Each polypeptide in the dimer has 3.6 residues per turn, and a nonpolar group occurs every 3.5 residues, resulting in a slight winding, or twist, around the other polypeptide, forming a coiled coil. Arg-Ala-His-Glu-His-Thr-Asp is a likely repeat in the a helix of keratin. ☐ Val-Thr-Asp-Ala-Glu-Arg-His is a likely repeat in the a helix of keratin. ☐ The residues at positions b and c are less likely to be polar or charged because they are in contact with the solvent. ☐ Keratin molecules are very strong due…

What does this statement mean: "Upon folding of a protein many main chain amides replace their hydrogen bonds to water for those with other amide bonds"  Is this true for alpha helix in proline racemase? and is there a pattern?

PfCRT is found to have 10 peaks on a hydropathy plot given its primary sequence. Researchers also noted that each peak is comprised of about 30 amino acids. The digestive vacuole membrane is 45Å in Plasmodium species. Explain why researchers conclude there are 10 transmembrane helices from these two pieces of data.

Write a structural formula for a tetrapeptide composed of phenyl-alanine, glycine, aspartic acid, and histidine in which the phenylalanine is N-terminal and the histidine is C-terminal. How many different tetrapeptides could be written that fit the criteria in this question?

Membrane-spanning proteins are notoriously difficult to characterize by x-ray crystallography. Hollonut of VISA Toplon a. Explain how the information in the diagrams below can be used in the detection of membrane- spanning proteins consisting of alpha helices, given that the lipid portion of a typical bilayer is approximately 30 Å thick. Amino terminus 5.4 A (3.6 residues) b. Identify and briefly describe how the features of a transmembrane protein composed of ß-sheets differ from that above.

What would the order of migration be (bottom to top in the gel) in a SDS-PAGE for the following proteins? Concanavalin A (ConA) (a homotetramer of 106 kDa), lysozyme (a monomer of 14.3 kDa) & horse liver alcohol dehydrogenase (ADH) (a homodimer of 80 kDa). a. ADH, ConA, lysozyme b. ConA, ADH, lysozyme c. Lysozyme, ADH, ConA Od. Lysozyme, ConA, ADH

Assume a fragment of two-stranded antiparallel β-structure is 3.3 nm long. What is the approximate number of amino acids in this fragment?

is it true that aplha and beta are made up of same amino acids but Beta chain is longer than alpha chain？what is other difference and similarity？is the amino aicd sequence exactly the same as well？are their structure the same ？