Chains and heterogens:
PDB Chain Sequences:
>1t91A (A:) mtsrkkvllkviilgdsgvgktslmnqyvnkkfsnqykatigadfltkevmvddrlvtmq iwdtaglerfqslgvafyrgadccvlvfdvtapntfktldswrdefliqasprdpenfpf vvlgnkidlenrqvatkraqawcysknnipyfetsakeainveqafqtiarnalkqetev elynefpepikldkndrakasaescsc
>1t91A (A:) vllkviilgdsgvgktslmnqyvnkkfsnqykatigadfltkevmvddrlvtmqiwdtag lerfqslgvafyrgadccvlvfdvtapntfktldswrdefliqasprdpenfpfvvlgnk idlenrqvatkraqawcysknnipyfetsakeainveqafqtiarnalkqetevel
>1t91B (B:) mtsrkkvllkviilgdsgvgktslmnqyvnkkfsnqykatigadfltkevmvddrlvtmq iwdtaglerfqslgvafyrgadccvlvfdvtapntfktldswrdefliqasprdpenfpf vvlgnkidlenrqvatkraqawcysknnipyfetsakeainveqafqtiarnalkqetev elynefpepikldkndrakasaescsc
>1t91B (B:) vllkviilgdsgvgktslmnqyvnkkfsnqykatigadfltkevmvddrlvtmqiwdtag lerfqslgvafyrgadccvlvfdvtapntfktldswrdefliqasprdpenfpfvvlgnk idlenrqvatkraqawcysknnipyfetsakeainveqafqtiarnalkqetevel
>1t91C (C:) mtsrkkvllkviilgdsgvgktslmnqyvnkkfsnqykatigadfltkevmvddrlvtmq iwdtaglerfqslgvafyrgadccvlvfdvtapntfktldswrdefliqasprdpenfpf vvlgnkidlenrqvatkraqawcysknnipyfetsakeainveqafqtiarnalkqetev elynefpepikldkndrakasaescsc
>1t91C (C:) vllkviilgdsgvgktslmnqyvnkkfsnqykatigadfltkevmvddrlvtmqiwdtag lerfqslgvafyrgadccvlvfdvtapntfktldswrdefliqasprdpenfpfvvlgnk idlenrqvatkraqawcysknnipyfetsakeainveqafqtiarnalkqetevel
>1t91D (D:) mtsrkkvllkviilgdsgvgktslmnqyvnkkfsnqykatigadfltkevmvddrlvtmq iwdtaglerfqslgvafyrgadccvlvfdvtapntfktldswrdefliqasprdpenfpf vvlgnkidlenrqvatkraqawcysknnipyfetsakeainveqafqtiarnalkqetev elynefpepikldkndrakasaescsc
>1t91D (D:) vllkviilgdsgvgktslmnqyvnkkfsnqykatigadfltkevmvddrlvtmqiwdtag lerfqslgvafyrgadccvlvfdvtapntfktldswrdefliqasprdpenfpfvvlgnk idlenrqvatkraqawcysknnipyfetsakeainveqafqtiarnalkqetevel