3. Amino acids projet from oach polypeptide backbone in a B-sheet in an alternat
ID: 191747 • Letter: 3
Question
3. Amino acids projet from oach polypeptide backbone in a B-sheet in an alternating fashion (one above the plane and the next below the plane- see Fig 3.8B). Consider the following protein sequence: Leu-Lys-Val-Asp- lle-Ser-Leu-Arg-Leu-Lys-llo-Arg-Phe-Glue. (Hint: consider Fig 3-2) a. Is there a pattern to these amino acids? If so, what is it? b. What does this sequence of amino acids mean for the hydro-phobicity/philicty of the resulting -sheet? er levels of protein structure? If so c. Can you make a prediction ab what prediction would you make?Explanation / Answer
Answer:
3. (a) The amino acid sequence consists of alternating nonpolar and charged or polar amino acids.
(b) The resulting strand in a beta sheet would therefore be polar on one side and hydrophobic on the other. Such a strand would probably be surrounded on either side by similar strands that together from a beta sheet with a hydrophobic and polar face.
(c) In a protein, such a beta sheet would be positioned so that the hydrophobic side would face the protein's interior and the polar side would be on its surface, exposed to the water outside.