Protein tyrosine phosphatases (PTPs) are promising drug targets for treating a wide range of diseases such as diabetes, cancer, and neurological disorders, but their conserved active sites have complicated the design of selective therapeutics. This study examines the allosteric inhibition of PTP1B by amorphadiene (AD), a terpenoid hydrocarbon that is an unusually selective inhibitor. Molecular dynamics (MD) simulations carried out in this study suggest that AD can stably sample multiple neighboring sites on the allosterically influential C-terminus of the catalytic domain. Binding to these sites requires a disordered α7 helix, which stabilizes the PTP1B−AD complex and may contribute to the selectivity of AD for PTP1B over TCPTP. Intriguingly, the binding mode of AD differs from that of the most well-studied allosteric inhibitor of PTP1B. Indeed, biophysical measurements and MD simulations indicate that the two molecules can bind simultaneously. Upon binding, both inhibitors destabilize the α7 helix by disrupting interactions at the α3−α7 interface and prevent the formation of hydrogen bonds that facilitate closure of the catalytically essential WPD loop. These findings indicate that AD is a promising scaffold for building allosteric inhibitors of PTP1B and illustrate, more broadly, how unfunctionalized terpenoids can engage in specific interactions with protein surfaces.

Photosensory domains are powerful tools for placing proteins under optical control, but their integration into light-sensitive chimeras is often challenging. Many designs require structural iterations, and direct comparisons of alternative approaches are rare. This study uses protein tyrosine phosphatase 1B (PTP1B), an influential regulatory enzyme, to compare three architectures for controlling PTPs with light: a protein fusion, an insertion chimera, and a split construct. All three designs permitted optical control of PTP1B activity in vitro (i.e., kinetic assays of purified enzyme) and in mammalian cells; photoresponses measured under both conditions, while different in magnitude, were linearly correlated. The fusion- and insertion-based architectures exhibited the highest dynamic range and maintained native localization patterns in mammalian cells. A single insertion architecture enabled optical control of both PTP1B and TCPTP, but not SHP2, where the analogous chimera was active but not photoswitchable. Findings suggest that PTPs are highly tolerant of domain insertions and support the use of in vitro screens to evaluate different optogenetic designs.

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Protein tyrosine phosphatases (PTPs) are promising drug targets for treating a wide range of diseases such as diabetes, cancer, and neurological disorders, but their conserved active sites have complicated the design of selective therapeutics. This study examines the inhibition of PTP1B by amorphadiene (AD), an unusually selective terpenoid inhibitor. Molecular dynamics (MD) simulations in this study suggest that AD can sample two neighboring sites on the allosterically influential C-terminus of the catalytic domain. Binding to these sites requires a disordered $\alpha$7 helix, which stabilizes the PTP1B-AD complex and may contribute to the selectivity of AD for PTP1B over TCPTP, its closest homologue. The binding mode of AD differs from that of a previously reported allosteric inhibitor; notably, biophysical measurements and MD simulations indicate that the two molecules can bind simultaneously. Upon binding, both inhibitors destabilize the α7 helix and disrupt hydrogen bonds that facilitate closure of the catalytically essential WPD loop. These findings suggest that AD is a promising scaffold for building allosteric inhibitors of PTP1B and illustrate, more broadly, how unfunctionalized terpenoids can engage in specific interactions with protein surfaces.

Chamber process gas composition during lyophilization is quantified for several representative formulations using residual gas analysis. The advantages of the technique lie in its ability to measure the relative concentration of various species during the lyophilization process. This feature gives residual gas analysis utility in a host of applications from endpoint determination to quality assurance. In contrast to other methods, residual gas analysis is able to determine oxygen and water vapor content in the process gas. These compounds have been shown to directly influence product shelf life. With these results, residual gas analysis technique presents a potential new method for real-time lyophilization process control and improved understanding of formulation and processing effects for lyophilized pharmaceutical products.