4D6D:
reference: Toward Efficient Enzymes for the Generation of Universal Blood through Structure-Guided Directed Evolution., Kwan DH, Constantinescu I, Chapanian R, Higgins MA, Kotzler MP, Samain E, Boraston AB, Kizhakkedathu JN, Withers SG, J Am Chem Soc. 2015 Apr 24. PMID: 25870881

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