TY - JOUR
T1 - Site-specific protection and dual labeling of human epidermal growth factor (hEGF) for targeting, imaging, and cargo delivery
AU - Sonntag, M.H.
AU - Ibach, J.
AU - Nieto, L.
AU - Verveer, P.J.
AU - Brunsveld, L.
PY - 2014/5/12
Y1 - 2014/5/12
N2 - Well-defined human epidermal growth factor (hEGF) constructs featuring selectively addressable labels are urgently needed to address outstanding questions regarding hEGF biology. A protein-engineering approach was developed to provide access to hEGF constructs that carry two cysteine-based site-specific orthogonal labeling sites in multi-milligram quantities. Also, a site-selective (de)protection and labeling approach was devised, which allows selective modification of these hEGF constructs. The hEGF, featuring three native disulfide bonds, was expressed featuring additional sulfhydryl groups, in the form of cysteine residues, as orthogonal ligation sites at both the N and C termini. Temporary protection of the N-terminal cysteine unit, in the form of a thiazolidine ring, avoids interference with protein folding and enables sequential labeling in conjunction with the cysteine residue at the C terminus. Based on thus-generated hEGF constructs, sequential and site-specific labeling with a variety of molecular probes could be demonstrated, thus leading to a biological fully functional hEGF with specifically incorporated fluorophores or protein cargo and native cellular targeting and uptake profiles. Thus, this novel strategy provides a robust entry to high-yielding access of hEGF and rapid and easy site-specific and multifunctional dual labeling of this growth factor.
AB - Well-defined human epidermal growth factor (hEGF) constructs featuring selectively addressable labels are urgently needed to address outstanding questions regarding hEGF biology. A protein-engineering approach was developed to provide access to hEGF constructs that carry two cysteine-based site-specific orthogonal labeling sites in multi-milligram quantities. Also, a site-selective (de)protection and labeling approach was devised, which allows selective modification of these hEGF constructs. The hEGF, featuring three native disulfide bonds, was expressed featuring additional sulfhydryl groups, in the form of cysteine residues, as orthogonal ligation sites at both the N and C termini. Temporary protection of the N-terminal cysteine unit, in the form of a thiazolidine ring, avoids interference with protein folding and enables sequential labeling in conjunction with the cysteine residue at the C terminus. Based on thus-generated hEGF constructs, sequential and site-specific labeling with a variety of molecular probes could be demonstrated, thus leading to a biological fully functional hEGF with specifically incorporated fluorophores or protein cargo and native cellular targeting and uptake profiles. Thus, this novel strategy provides a robust entry to high-yielding access of hEGF and rapid and easy site-specific and multifunctional dual labeling of this growth factor.
KW - drug delivery
KW - growth factors
KW - labeling
KW - protein modifications
KW - thiazolidines
UR - http://www.scopus.com/inward/record.url?scp=84928204051&partnerID=8YFLogxK
U2 - 10.1002/chem.201304090
DO - 10.1002/chem.201304090
M3 - Article
C2 - 24700787
SN - 0947-6539
VL - 20
SP - 6019
EP - 6026
JO - Chemistry : A European Journal
JF - Chemistry : A European Journal
IS - 20
ER -