3U3B:
reference: Increasing sequence diversity with flexible backbone protein design: the complete redesign of a protein hydrophobic core., Murphy GS, Mills JL, Miley MJ, Machius M, Szyperski T, Kuhlman B, Structure. 2012 Jun 6;20(6):1086-96. Epub 2012 May 24. PMID: 22632833

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