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A genome‐inspired DNA ligand for the affinity capture of insulin and insulin‐like growth factor‐2
Author(s) -
Xiao Junfeng,
Carter Jennifer A.,
Frederick Kimberley A.,
McGown Linda B.
Publication year - 2009
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.200900060
Subject(s) - intramolecular force , insulin , surface plasmon resonance , chemistry , circular dichroism , dna , ligand (biochemistry) , biochemistry , stereochemistry , biology , receptor , materials science , nanotechnology , nanoparticle , endocrinology
Abstract The insulin‐linked polymorphic region (ILPR) of the human insulin gene contains tandem repeats of similar G‐rich sequences, some of which form intramolecular G‐quadruplex structures in vitro . Previous work showed affinity binding of insulin to an intramolecular G‐quadruplex formed by ILPR variant a. Here, we report on interactions of insulin and the highly homologous insulin‐like growth factor‐2 (IGF‐2) with ILPR variants a, h, and i. Circular dichroism indicated intramolecular G‐quadruplex formation for variants a and h. Affinity MALDI MS and surface plasmon resonance were used to compare protein capture and binding strengths. Insulin and IGF‐2 exhibited high binding affinity for variants a and h but not i, indicating the involvement of intramolecular G‐quadruplexes. Interaction between insulin and variant a was unique in the appearance of two binding interactions with K D ∼ 10 –13 M and K D ∼ 10 –7 M, which was not observed for insulin with variant h ( K D ∼ 10 –8 M) or IGF‐2 with either variant ( K D s ∼ 10 –9 M). The results provide a basis for the design of DNA binding ligands for insulin and IGF‐2 and support a new approach to discovery of DNA affinity binding ligands based on genome‐inspired sequences rather than the traditional combinatorial selection route to aptamer discovery.