Secondary structural features are labeled corresponding to primary sequence: A: Ala2-Phe6, B: Ser14-Ser18, C: Ala21-Lys31, D: Val33-Thr49, E: Ala50-Ala60, F: Ile61-Gly69, G: Ser72-Ile76, H: Pro83-Asn94, I: Glu102-Glu108, J: Leu112-His116, K: Val121-Leu125, L: Leu131-Val134, M: His140-Met144, N: Thr151-Phe156, O: Asn158-Gly161, P: Thr162-Ile163, Q: Ile171-Tyr175.