As long as we're on the K&K track, there's also Consistency principle for protein design, which might be of interest.

Or there's the aardvark design principle, which is "change everything to aardvark, aardvark, aardvark, make helices, and hope for the best". (Still haven't gotten a complete aardvark yet, however.)

but am astounded that there's an actual **theory** behind it!