Table of contents

1. Introduction to Biochemistry4h 34m
2. Water3h 23m
3. Amino Acids8h 10m
4. Protein Structure10h 4m
5. Protein Techniques14h 5m
6. Enzymes and Enzyme Kinetics13h 38m
7. Enzyme Inhibition and Regulation 8h 42m
8. Protein Function 9h 41m
9. Carbohydrates7h 49m
10. Lipids5h 49m
11. Biological Membranes and Transport 6h 37m
12. Biosignaling9h 45m
Review 1: Nucleic Acids, Lipids, & Membranes2h 47m
Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway3h 12m
Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism2h 26m
Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation1h 48m

5. Protein Techniques

Tandem Mass Spectrometry

Biochemistry

5. Protein Techniques

Tandem Mass Spectrometry

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Multiple Choice

In your tandem mass-spectrometry of a pure protein, you focused a fragment with an m/z of 1,268 through the process & into the second mass-spec and found y-ion peaks of 1,137 and 1,022. The mass in Daltons for the possible relevant amino acids are provided: Y (163), N (114), W (186), D (115), G (57), L (113) and M (131). What is the order of the first two amino acid residues in the 1,268 fragment from N-terminal to C-terminal?

N-M.

N-Y.

M-D.

M-L.

D-N.

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Verified step by step guidance

Understand the problem: You are given a fragment with an m/z of 1,268 and y-ion peaks of 1,137 and 1,022. You need to determine the order of the first two amino acid residues from N-terminal to C-terminal in this fragment.

Calculate the mass difference between the fragment and the first y-ion peak: Subtract the m/z of the y-ion peak (1,137) from the m/z of the fragment (1,268) to find the mass of the first amino acid residue.

Calculate the mass difference between the first and second y-ion peaks: Subtract the m/z of the second y-ion peak (1,022) from the m/z of the first y-ion peak (1,137) to find the mass of the second amino acid residue.

Match the calculated mass differences to the given amino acid masses: Compare the calculated mass differences to the provided masses of amino acids (Y, N, W, D, G, L, M) to identify the amino acids corresponding to each mass difference.

Determine the order of the amino acids: Based on the identified amino acids from the mass differences, determine the order from N-terminal to C-terminal in the fragment.