Identification of Hetero-aggregates in Antibody Co-formulations by Multi-dimensional Liquid Chromatography Coupled to Mass Spectrometry

Antibody combination therapies have become viable therapeutic treatment options for certain severe diseases such as cancer. The co-formulation production approach is intrinsically associated with more complex drug product variant profiles and creates more challenges for analytical control of drug product quality. In addition to various individual quality attributes, those arising from the interactions between the antibodies also potentially emerge through co-formulation. In this study, we describe the development of a widely applicable multi-dimensional liquid chromatography coupled to tandem mass spectrometry method for antibody homo- versus hetero-aggregate characterization. The co-formulation of trastuzumab and pertuzumab was used, a challenging model system, comprising two monoclonal antibodies with very similar physicochemical properties. The data presented demonstrate the high stability of the co-formulation, where only minor aggregate formation is observed upon product storage and accelerated temperature or light-stress conditions. The results also show that the homo- and hetero-aggregates, formed in low and comparable proportions, are only marginally impacted by the formulation and product storage conditions. No preferential formation of hetero-aggregates, in comparison to the already existing pertuzumab and trastuzumab homo-aggregates, was observed.

Quantum simulation of the Klein paradox with trapped ions

We report on quantum simulations of relativistic scattering dynamics using trapped ions. The simulated state of a scattering particle is encoded in both the electronic and vibrational state of an ion, representing the discrete and continuous components of relativistic wave functions. Multiple laser fields and an auxiliary ion simulate the dynamics generated by the Dirac equation in the presence of a scattering potential. Measurement and reconstruction of the particle wave packet enables a frame-by-frame visualization of the scattering processes. By precisely engineering a range of external potentials we are able to simulate text book relativistic scattering experiments and study Klein tunneling in an analogue quantum simulator. We describe extensions to solve problems that are beyond current classical computing capabilities.

Efficient enzymatic production of the bacterial second messenger c-di-GMP by the diguanylate cyclase YdeH from E. coli

Cyclic di-GMP (c-di-GMP) is an almost universal bacterial second messenger involved in the regulation of cell surface-associated traits and the persistence of infections. GGDEF and EAL domain-containing proteins catalyse c-di-GMP synthesis and degradation, respectively. We report the enzymatic large-scale synthesis of c-di-GMP, making use of the GGDEF domain-containing protein YdeH from Escherichia coli. Overexpression and purification of YdeH have been established, and the conditions for c-di-GMP synthesis were optimised. In contrast to the chemical synthesis of c-di-GMP, enzymatic c-di-GMP production is a one-step reaction that can easily be performed with the equipment of a standard biochemical lab. The protocol allows the production of milligram amounts of c-di-GMP within 1 day and paves the way for extensive biochemical and biophysical studies on c-di-GMP-mediated processes.

Realization of a quantum walk with one and two trapped ions

We experimentally demonstrate a quantum walk on a line in phase space using one and two trapped ions. A walk with up to 23 steps is realized by subjecting an ion to state-dependent displacement operations interleaved with quantum coin tossing operations. To analyze the ion's motional state after each step we apply a technique that directly maps the probability density distribution onto the ion's internal state. The measured probability distributions and the position's second moment clearly show the nonclassical character of the quantum walk. To further highlight the difference between the classical (random) and the quantum walk, we demonstrate the reversibility of the latter. Finally, we extend the quantum walk by using two ions, giving the walker the additional possibility to stay instead of taking a step.