All three helices are partially folded but the B1 core can be considered as only very weakly structured. Only H5 and H6 make contact through the B1 core, through interactions between L165 at the C-terminus of H5 and V173 at the N-terminus of H6. H1 is only connected to the B1 core in the native state via V103, but the Φ-value of V103A is zero, suggesting that H1 does not contribute to the formation of the B1 core in the transition state (TS). (Note, however, that H1 and H5 do interact in the TS, through sidechain contacts on the central core side of the helices).