"Antibody-breeding" approach potentially generates therapeutic/diagnostic antibody mutants with greater performance than native antibodies. Therein, antibody fragments (e.g., single-chain Fv fragments; scFvs) with a variety of mutations are displayed on bacteriophage to generate diverse phage-antibody libraries. Rare clones with improved functions are then selected via panning against immobilized or tagged target antigens. However, this selection process often ended unsuccessful, mainly due to the biased propagation of phage-antibody clones and the competition with a large excess of undesirable clones with weaker affinities. To break radically from such panning-inherent problems, we developed a novel method, clonal array profiling of scFv-displaying phages (CAP), in which colonies of the initial bacterial libraries are examined one-by-one in microwells. Progenies of scFv-displaying phages generated are, if show sufficient affinity to target antigen, captured in the microwell via pre-coated antigen and detected using a luciferase-fused anti-phage scFv. The advantage of CAP was evidenced by its application with a small error-prone-PCR-based library (~ 10
5
colonies) of anti-cortisol scFvs. Only two operations, each surveying only ~ 3% of the library (9,400 colonies), provided five mutants showing 32–63-fold improved
K
a
values (> 10
10
M
−1
), compared with the wild-type scFv (
K
a
= 3.8 × 10
8
M
−1
), none of which could be recovered via conventional panning procedures operated for the entire library.
We report an ultra‐fast helix induction and subsequent static helicity memory in poly(biphenylylacetylene) (PBPA‐A) assisted by a catalytic amount of nonracemic ammonium salts comprised of non‐coordinating tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate (BArF−) as a counter anion. The remarkable acceleration of the helix‐induction rate in PBPA‐A accompanied by the significant amplification of the asymmetry relies on the two methoxymethoxy groups of the biphenyl pendants, which can gain access to enfold the chiral ammoniums in a crown‐ether manner in specific aromatic solvents, leading to ultra‐fast helicity induction, which is completed within 30 s. In aromatic solvents, helicity memory is lost rapidly, but is quite stable in long‐chain hydrocarbons. The best use of specific solvents for helicity induction and static helicity memory, respectively, provides a highly sensitive chirality sensing system toward a small amount of chiral amines and amino acids when complexed with BArF−.
We report an ultra‐fast helix induction and subsequent static helicity memory in poly(biphenylylacetylene) (PBPA‐A) assisted by a catalytic amount of nonracemic ammonium salts comprised of non‐coordinating tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate (BArF−) as a counter anion. The remarkable acceleration of the helix‐induction rate in PBPA‐A accompanied by the significant amplification of the asymmetry relies on the two methoxymethoxy groups of the biphenyl pendants, which can gain access to enfold the chiral ammoniums in a crown‐ether manner in specific aromatic solvents, leading to ultra‐fast helicity induction, which is completed within 30 s. In aromatic solvents, helicity memory is lost rapidly, but is quite stable in long‐chain hydrocarbons. The best use of specific solvents for helicity induction and static helicity memory, respectively, provides a highly sensitive chirality sensing system toward a small amount of chiral amines and amino acids when complexed with BArF−.
Catalytic ultra‐fast helix induction and its static helicity memory in a poly(biphenylylacetylene) were achieved by using chiral ammonium salts, as reported by Katsuhiro Maeda, Eiji Yashima, and co‐workers in their Research Article (e202217020). The remarkable acceleration of the helix‐induction rate accompanied by strong chiral amplification relies on crown‐ether‐like specific intermolecular complex formation of the two methoxymethoxy groups of the biphenyl pendants with chiral ammonium species.
Catalytic ultra‐fast helix induction and its static helicity memory in a poly(biphenylylacetylene) were achieved by using chiral ammonium salts, as reported by Katsuhiro Maeda, Eiji Yashima, and co‐workers in their Research Article (e202217020). The remarkable acceleration of the helix‐induction rate accompanied by strong chiral amplification relies on crown‐ether‐like specific intermolecular complex formation of the two methoxymethoxy groups of the biphenyl pendants with chiral ammonium species.
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