title: Impact of site-specific PEGylation on the conformational stability and folding rate of the Pin WW domain depends strongly on PEG oligomer length.
abstract: Protein PEGylation is an effective method for reducing the proteolytic susceptibility, aggregation propensity, and immunogenicity of protein drugs. These pharmacokinetic challenges are fundamentally related to protein conformational stability, and become much worse for proteins that populate the unfolded state under ambient conditions. If PEGylation consistently led to increased conformational stability, its beneficial pharmacokinetic effects could be extended and enhanced. However, the impact of PEGylation on protein conformational stability is currently unpredictable. Here we show that appending a short PEG oligomer to a single Asn side chain within a reverse turn in the WW domain of the human protein Pin 1 increases WW conformational stability in a manner that depends strongly on the length of the PEG oligomer: shorter oligomers increase folding rate, whereas longer oligomers increase folding rate and reduce unfolding rate. This strong length dependence is consistent with the possibility that the PEG oligomer stabilizes the transition and folded states of WW relative to the unfolded state by interacting favorably with side-chain or backbone groups on the WW surface.
authors.affiliation: Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
authors.forename: Brijesh K
authors.initials: BK
authors.lastname: Pandey
authors.forename: Mason S
authors.initials: MS
authors.lastname: Smith
authors.forename: Chad
authors.initials: C
authors.lastname: Torgerson
authors.forename: Paul B
authors.initials: PB
authors.lastname: Lawrence
authors.forename: Sam S
authors.initials: SS
authors.lastname: Matthews
authors.forename: Emily
authors.initials: E
authors.lastname: Watkins
authors.forename: Melinda L
authors.initials: ML
authors.lastname: Groves
authors.forename: Maxim B
authors.initials: MB
authors.lastname: Prigozhin
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Price
mesh_terms: D006801:Humans; D008958:Models, Molecular; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019696:Peptidylprolyl Isomerase / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D055550:Protein Stability; D017434:Protein Structure, Tertiary
chemical_list: D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D011092:Polyethylene Glycols; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase