Answer:


Yes.

In this figure I coloured 1 residue purple in each turn in erabutoxin. The turn around residue 9 (top right purple residue in the static figure) is a bit bigger and thus a bit poorer defined). I further added all prolines in gray, and all cysteines in yellow. You see that each turn is protected by either a proline or a cysteine bridge, or both. Just the turn on the top isn't. And if we look at the residues in this turn (Arg and Phe) then we might hope that one student realizes that a positive charge next to a aromatic group looks very much like many neuro transmitters.... And that brings the hypothesis that the top turn might be the 'active site' and might work by mimicking a neurotransmitter.

Sometimes students count the beginning of the loop just after the last strand (around residue 56) also as a turn. That is not wrong, but it also doesn't change anything in the story.

Sometimes students do not count the turn just after the fourth strand (because they think it is a strand moving into a loop, or some kind of similar reasoning). That is wrong. As long as they realise that there are a series of chain-reversals, and only the 'top-one' is a clean β-turn

Further things to be found is that the protein comes from a black-and-white blocked seasnake, and it is very, very toxic...