[DrScientist]

No one is arguing reuse is a surprise - there used to be a joke in the early days of protein fold prediction - that if the protein amino acid sequence was a certain length - you just predict TIM barrel and you'd be right.

the question is a separate one - how much of protein universe of folds have already been seen?

[jyounker]

So we're in agreement. The expectation is that biochemistry here on Earth only produces a small proportion of the possible structures.