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Sortase-catalyzed transformations that improve the properties of cytokines
Maximilian W. Popp, Stephanie K. Dougan, Tzu-Ying Chuang, Eric Spooner, Hidde L. Ploegh and Donald F. Steiner
Proceedings of the National Academy of Sciences of the United States of America
Vol. 108, No. 8 (February 22, 2011), pp. 3169-3174
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/41060900
Page Count: 6
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Recombinant protein therapeutics often suffer from short circulating half-life and poor stability, necessitating multiple injections and resulting in limited shelf-life. Conjugation to polyethylene glycol chains (PEG) extends the circulatory half-life of many proteins, but the methods for attachment often lack specificity, resulting in loss of biological activity. Using four-helix bundle cytokines as an example, we present a general platform that uses sortasemediated transpeptidation to facilitate site-specific attachment of PEG to extend cytokine half-life with full retention of biological activity. Covalently joining the N and C termini of proteins to obtain circular polypeptides, again executed using sortase, increases thermal stability. We combined both PEGylation and circularization by exploiting two distinct sortase enzymes and the use of a molecular suture that allows both site-specific PEGylation and covalent closure. The method developed is general, uses a set of easily accessible reagents, and should be applicable to a wide variety of proteins, provided that their termini are not involved in receptor binding or function.
Proceedings of the National Academy of Sciences of the United States of America © 2011 National Academy of Sciences