Which of the following base pairs could proteins distinguish

Which of the following base pairs could proteins distinguish, and why?

a. Major groove base pairs (GC/CG, AT/TA, GC/TA, GC/AT)

b. Minor groove base pairs (GC/CG, AT/TA, GC/TA, GC/AT)

Solution

a. Major groove base pairs (GC/CG, AT/TA, GC/TA, GC/AT)

Answer:

The pattern DNA recognition elements are going to be recognized by protein complimentary functional groups mainly in major groove in which four kinds of bases are distinguishable each other. So that, GC are distinguishable for CG & AT is distinguishable for TA similarly the remaining GC/TA, GC/AT each other. The minor groove in which G-C are indistinguishable to that of C-G however, the pattern of AT is similar to TA