Ch.5 - Biological MoleculesWorksheetSee all chapters
All Chapters
Ch.1 - Introduction to Biology
Ch.2 - Chemistry
Ch.3 - Water
Ch.4 - Carbon
Ch.5 - Biological Molecules
Ch.6 - Cells
Ch.7 - The Membrane
Ch.8 - Energy and Metabolism
Ch.9 - Respiration
Ch.10 - Photosynthesis
Ch.11 - Cell Signaling
Ch.12 - Cell Division
Ch.13 - Meiosis
Ch.14 - Mendelian Genetics
Ch.15 - Chromosomal Theory of Inheritance
Ch.16 - DNA Synthesis
Ch.17 - Gene Expression
Ch.18 - Regulation of Expression
Ch.19 - Viruses
Ch.20 - Biotechnology
Ch.21 - Genomics
Ch.22 - Development
Ch.23 - Evolution by Natural Selection
Ch.24 - Evolution of Populations
Ch.25 - Speciation
Ch.26 - History of Life on Earth
Ch.27 - Phylogeny
Ch.28 - Prokaryotes
Ch.29 - Protists
Ch.30 - Plants
Ch.31 - Fungi
Ch.32 - Overview of Animals
Ch.33 - Invertebrates
Ch.34 - Vertebrates
Ch.35 - Plant Anatomy
Ch.36 - Vascular Plant Transport
Ch.37 - Soil
Ch.38 - Plant Reproduction
Ch.39 - Plant Sensation and Response
Ch.40 - Animal Form and Function
Ch.41 - Digestive System
Ch.42 - Circulatory System
Ch.43 - Immune System
Ch.44 - Osmoregulation and Excretion
Ch.45 - Endocrine System
Ch.46 - Animal Reproduction
Ch.47 - Nervous System
Ch.48 - Sensory Systems
Ch.49 - Muscle Systems
Ch.50 - Ecology
Ch.51 - Animal Behavior
Ch.52 - Population Ecology
Ch.53 - Community Ecology
Ch.54 - Ecosystems
Ch.55 - Conservation Biology
Sections
Polymers
Carbohydrates
Proteins
Nucleic Acids
Lipids
Additional Practice
Cumulative Macromolecules

Solution: A single, 18-amino acid peptide chain is to be assigned from the following experimental information below, your job is to provide the full triple lettercode sequence (if possible) and show your logic behind your answer.(i) Amino acid analysis of the native peptide: Cx6, Rx2, Ex1, Yx1, Px1, Vx1, Ax1, Mx1, Wx1, Lx1, Kx1, and Tx1.(ii) Dinitrofluorobenzene (FDNB) analysis indicated the presence of C on reaction of the native peptide.(iii) The native peptide is subjected to DTT and Pepsin Digestion of the native peptide produced 4 peptide fragments that were then exposed to Edman degradation analysis, they provided the following sequence information:Fragment 1: YVPRMAC          Fragment 2: CC          Fragment 3: LCKETC          Fragment 4: WRC(iv) Following disulfide bond reduction, Cyanogen Bromide digestion of the original intact peptide provided 2 peptide, one 6mer + homoserine lactone and one 11mer.(v) The resultin 11mer was HPLC isolated and exposed to TCEP, this peptide was subjected to Trypsin digestion followed by amino acid analysis. The Trypsin digested peptide fragments: A, B, andC, were assigned the following amino acid composition:Fragment A: Cx2, Lx1, Kx1          Fragment B: Tx1, Ex1, Cx1          Fragment C: Cx1, Wx1, Ax1, Rx1

Problem

A single, 18-amino acid peptide chain is to be assigned from the following experimental information below, your job is to provide the full triple lettercode sequence (if possible) and show your logic behind your answer.

(i) Amino acid analysis of the native peptide: Cx6, Rx2, Ex1, Yx1, Px1, Vx1, Ax1, Mx1, Wx1, Lx1, Kx1, and Tx1.

(ii) Dinitrofluorobenzene (FDNB) analysis indicated the presence of C on reaction of the native peptide.

(iii) The native peptide is subjected to DTT and Pepsin Digestion of the native peptide produced 4 peptide fragments that were then exposed to Edman degradation analysis, they provided the following sequence information:

Fragment 1: YVPRMAC          Fragment 2: CC          Fragment 3: LCKETC          Fragment 4: WRC

(iv) Following disulfide bond reduction, Cyanogen Bromide digestion of the original intact peptide provided 2 peptide, one 6mer + homoserine lactone and one 11mer.

(v) The resultin 11mer was HPLC isolated and exposed to TCEP, this peptide was subjected to Trypsin digestion followed by amino acid analysis. The Trypsin digested peptide fragments: A, B, andC, were assigned the following amino acid composition:

Fragment A: Cx2, Lx1, Kx1          Fragment B: Tx1, Ex1, Cx1          Fragment C: Cx1, Wx1, Ax1, Rx1

Solution

(i) This will serve as the amino acid reference for the sequence analysis. The amino acids (AAs) that are key to the peptide's reaction to different chemicals and enzymes should be noted.

(ii) FDNB analysis determines the AA in the N terminal of the peptide:

C _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

(iii) DTT is used for reduction of disulfide bonds to recover the linear primary structure. Pepsin digestion cleaves the N side of the amino acids L, F, W, and Y. Thus, these amino acids should be the starting AA of each fragment, except for the established first AA, which is C. Thus Fragment 2 is first in the sequence.

C C _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

(iv) Cyanogen bromide (CNBr) cleaves the C-side of Met (M). Formation of homoserine lactone is just the side reaction of met with the reagent. There is only one M in the sequence, giving only one point of cleavage. Thus, there are only 2 fragments. Homoserine lactone is M, which makes it the 7th amino acid.Referring to the fragments in (iii), the sequence would be:

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