Which technique is commonly used for protein identification by matching experimental mass spectra with theoretical spectra?
Explanation: The correct answer is B) Mass spectrometry. Mass spectrometry is commonly used for protein identification. In particular, techniques such as tandem mass spectrometry (MS/MS) can generate experimental mass spectra of peptides derived from protein digestion. These spectra are then matched against theoretical spectra in protein databases to identify the proteins present in the sample.
Which technique allows for the determination of a protein's amino acid sequence?
Explanation: The correct answer is D) Edman degradation. Edman degradation is a technique used for determining the amino acid sequence of a protein. It involves sequentially cleaving off the N-terminal amino acid residue of the protein, which can then be identified and quantified. By repeating this process, the complete amino acid sequence of the protein can be determined.
Which technique is commonly used to measure the molecular weight and size of proteins?
Explanation: The correct answer is C) Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). SDS-PAGE is commonly used to measure the molecular weight and size of proteins. In this technique, proteins are separated based on their molecular weight using an electric field applied to a gel matrix. The migration distance of the proteins is inversely proportional to their molecular weight, allowing for estimation of protein sizes based on the comparison with known protein standards.
Which technique allows for the determination of protein-protein interactions?
Explanation: The correct answer is D) Co-immunoprecipitation (Co-IP). Co-immunoprecipitation is a technique commonly used to determine protein-protein interactions. In Co-IP, a target protein of interest is immunoprecipitated using an antibody specific to that protein. During the immunoprecipitation process, interacting proteins can co-precipitate with the target protein, allowing for the identification and characterization of protein-protein interactions.
Which technique allows for the analysis of protein expression levels in a complex mixture?
Explanation: The correct answer is B) Mass spectrometry. Mass spectrometry, particularly quantitative mass spectrometry techniques, allows for the analysis of protein expression levels in a complex mixture. By comparing the relative abundance of peptides or protein fragments in different samples, changes in protein expression can be determined. This information provides insights into the characterization of proteins and their roles in biological processes.