Consider five proteins with the properties shown in the following table. Answer

Question

Consider five proteins with the properties shown in the following table. Answer the questions below about these proteins and justify your answers. 5. Protein Subunit mass (Da) Native mass (Da) 10,000 15,000 20,000 25,000 30,000 40,000 120,000 20,000 75,000 60,000 a) Which protein would migrate the slowest in an SDS-PAGE? b) Which protein would migrate the fast in a Native-PAGE? c) What is likely the quaternary structure (subunit composition) of each protein on the basis of the data in the table?

Explanation / Answer

a) Protein B migrates the slowest in an SDS-PAGE.

Explanation: Among the given five proteins (A-tetramer, B-octamer, C-monomer, D-trimer and E-dimer), protein B is the largest one, which migrates slower due to more resistance from the gel matrix.

b) Protein C migrates the fastest in a Native-PAGE.

Explanation: Since the protein retains its folded conformation, its hydrodynamic size and mobility on the gel will also vary with the nature of this conformation, i.e. higher mobility for more compact conformations, whereas lower mobility for larger structures like oligomers (dimers, trimers, tetramers, ..... up to decamers). Hence, protein C (that has more compact conformation) migrates the fastest among the given 5 proteins.

c) Proteins A, B, D and E are likely to be the quaternary structures based on the tabular data.

Explanation: Protein quaternary structure is the number and arrangement of multiple folded protein subunits in a multi-subunit complex. It includes organisations from simple dimers to large homo-oligomers and complexes with defined or variable numbers of subunits. Here, protein C is just a monomer, hence it can't have the quaternary structure.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.