A polypeptide is cleaved into peptides by treatment with trypsin and cyanogen bromide, and then the peptides are purified and sequenced. The sequences of the peptides are shown below. Trypsin peptides Cyanogen bromide peptides Based on sequences of the overlapping peptides generated by treatment with trypsin and cyanogen bromide (shown above), which of the following peptides represents the N-terminus of the original polypeptide? A. T-1 B. T-4 C. C-2 D. C-4 T-1 FENYA T-2 ELIMVPK T-3 NFEEGSK T-4 ITGLAIHQK T-5 GSMDPVALMTLR C-1 DPVALM C-2 VPKGSM C-3 ITGLAIHQKELIM C-4 TLRNFEEGSKFENYA

A sample of an unknown peptide was divided into two aliquots. One aliquot was treated with trypsin and the other was treated with cyanogen bromide. Given the following sequences (N-terminal to C-terminal) of the resulting fragments, deduce the sequence of the original peptide. Trypsin treatment Asn—Tyr—Asp—Met—Phe—Ala—Arg Asp—Trp—Asn—Arg Gln—Met—Tyr—Cys—Pro—Ile—Arg Gln—Cys Cyanogen bromide treatment Tyr—Cys—Pro—Ile—Arg—Asn—Tyr—Asp—Met   Asp—Trp—Asn—Arg—Gln—Met Phe—Ala—Arg—Gln—Cys

What general structural feature is shared by proteins that specifically form homodimers (but not homotrimers, homoteramers etc)? Only one answer is correct.     the surface consists of hydrophilic alpha-helix.   the surface is highly modified by post-translational modification.   the surface is permanently bound by chaperones.   the surface is unstructured.   the surface, or part of it, is self-complementary.

Given the following diagram of how protein AWESOME1 binds to it's target DNA, describe the potential effects of each of the 5 mutations shown below. The wild-type sequence of a helix #1 is also shown in the blue box, and all the mutations are in helix #1 (see numbers for identifying particular residues). a helix #1 R(1)-V-I-L-Y-F-W-I-M-Y-F-S-H-Y-W-R(16) #1 Predict the consequence of the following mutations: 1) Arg(1) to Glu 2) Arg(1) to Ala 3) Phe(6) to lle 4) Trp(7) to Phe 5) Met(9) to Pro in

A researcher has synthesized two peptides and needs to confirm whether the peptides were synthesized with the correct sequence using mass spectrometry. What is the sequence of the b4 and y7 ions for peptide GAMECHANGER?  The peptide SLISRAEFLAGVRVGV is digested with trypsin. Then the products of the digestion are subjected to ESI TOF-MS in positive ion mode with the peptides in a pH 2 solution. What peptide fragments will result and what are their m/z?

5) Snake venom surprisingly has been a found to be a rich source of biologically active peptides. One important class of peptides includes the bradykinin potentiating peptides which were the precursors to today's most commonly used antihypertensive drugs such as captopril or lisinopril. Let's say that you are investigating a new peptide in the bradykinin potentiating peptide class from Agkistrodon bilineatus (Mexican pit viper) venom. You suspect that the peptide has the following sequence: QWAQGRAPHPP After some harrowing experiments, you've collected and isolated a sample of this peptide. How will you confirm that the sequence is what you expected? Describe a sequence of chemical tests (at least 4) that you can do on this peptide that should give you enough information to deduce the sequence. Be sure to describe in detail each of the chemical analyses and the expected results of each.