>1i21B (B:) observed residues (from ATOM records)
mslpdgfyirrmeegdleqvtetlkvlttvgtitpesfcklikywneatvwndndkkimq
ynpmvivdkrtetvaatgniiierkiihelglcghiediavnskyqgqglgkllidqlvt
igfdygcykiildcdeknvkfyekcgfsnagvemqir