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Spatial hindrance‐based pro‐antibodies (pro‐Abs) are engineered antibodies to reduce monoclonal antibodies' (mAbs) on‐target toxicity using universal designed blocking segments that mask mAb antigen‐binding sites through spatial hindrance. By linking through protease substrates and linkers, these blocking segments can be removed site‐specifically. Although many types of blocking segments have been developed, such as coiled‐coil and hinge‐based Ab locks, the molecular structure of the pro‐Ab, particularly the region showing how the blocking fragment blocks the mAb, has not been elucidated by X‐ray crystallography or cryo‐EM. To achieve maximal effect, a pro‐Ab must have high antigen‐blocking and protease‐restoring efficiencies, but the unclear structure limits its further optimization. Here, we utilized molecular dynamics (MD) simulations to study the dynamic structures of a hinge‐based Ab lock pro‐Ab, pro‐Nivolumab, and validated the simulated structures with small‐ and wide‐angle X‐ray scattering (SWAXS). The MD results were closely consistent with SWAXS data (χ2best‐fit = 1.845, χ2allMD = 3.080). The further analysis shows a pronounced flexibility of the Ab lock (root‐mean‐square deviation = 10.90 Å), yet it still masks the important antigen‐binding residues by 57.3%–88.4%, explaining its 250‐folded antigen‐blocking efficiency. The introduced protease accessible surface area method affirmed better protease efficiency for light chain (33.03 Å2) over heavy chain (5.06 Å2), which aligns with the experiments. Overall, we developed MD‐SWAXS validation method to study the dynamics of flexible blocking segments and introduced methodologies to estimate their antigen‐blocking and protease‐restoring efficiencies, which would potentially be advancing the clinical applications of any spatial hindrance‐based pro‐Ab. [ABSTRACT FROM AUTHOR]

Probe design is a critical parameter in successful DNA and RNA target detection. In this proof-of-concept study, we evaluated the single-base mismatch recognition power of surface immobilized and self-assembled stem-loop hairpin DNA oligonucleotide probes modified to contain locked nucleic acid residues (LNA-HP). The stiffness change in conjunction with the stem opening of the interfacial molecules before and after hybridization led to clear variations of the overall film thickness or miniaturized nanospot height, which could be directly measured using an atomic force microscopy (AFM) nanolithography technique. Particularly, LNA-HP achieved highly differentiable readouts between perfectly complementary and singly mismatched targets (discrimination ratio as high as 2 to 3), outperforming the selectivity of its linear and hairpin counterparts with no LNA modification. 10.1021/ac902665c

Dissipative particle dynamics (DPD) was carried out to study the nucleation and crystal growth process of cerium dioxide (CeO2) nanoparticles in alcohol/water mixed solvents by homogeneous precipitation method. The results showed that properly selecting the sizes of CeO2 and water beads, and choosing the appropriate interaction parameters between beads are crucial in the simulation system. The nucleation and crystal growth process of CeO2 can be classified into four stages: induction, nuclei growth, crystal forming, and crystal aggregation, which could be reproduced from different initial CeO2 concentration and after different simulation time. The simulation results confirm that the effect of solvent on the nucleation and crystal growth of CeO2 nanoparticles are different at four stages and cannot be simply described by Derjaguin–Landau–Verwey–Overbeek theory or nucleation thermodynamics theory as proposed in the published literatures. Our work demonstrated that DPD methods can be applied to study nanoparticle forming process. [ABSTRACT FROM AUTHOR]

Spatial hindrance-based pro-antibodies (pro-Abs) are engineered antibodies to reduce monoclonal antibodies' (mAbs) on-target toxicity using universal designed blocking segments that mask mAb antigen-binding sites through spatial hindrance. By linking through protease substrates and linkers, these blocking segments can be removed site-specifically. Although many types of blocking segments have been developed, such as coiled-coil and hinge-based Ab locks, the molecular structure of the pro-Ab, particularly the region showing how the blocking fragment blocks the mAb, has not been elucidated by X-ray crystallography or cryo-EM. To achieve maximal effect, a pro-Ab must have high antigen-blocking and protease-restoring efficiencies, but the unclear structure limits its further optimization. Here, we utilized molecular dynamics (MD) simulations to study the dynamic structures of a hinge-based Ab lock pro-Ab, pro-Nivolumab, and validated the simulated structures with small- and wide-angle X-ray scattering (SWAXS). The MD results were closely consistent with SWAXS data (χ 2 best-fit  = 1.845, χ 2 allMD  = 3.080). The further analysis shows a pronounced flexibility of the Ab lock (root-mean-square deviation = 10.90 Å), yet it still masks the important antigen-binding residues by 57.3%-88.4%, explaining its 250-folded antigen-blocking efficiency. The introduced protease accessible surface area method affirmed better protease efficiency for light chain (33.03 Å 2 ) over heavy chain (5.06 Å 2 ), which aligns with the experiments. Overall, we developed MD-SWAXS validation method to study the dynamics of flexible blocking segments and introduced methodologies to estimate their antigen-blocking and protease-restoring efficiencies, which would potentially be advancing the clinical applications of any spatial hindrance-based pro-Ab., (© 2024 The Author(s). Protein Science published by Wiley Periodicals LLC on behalf of The Protein Society.)