Deviation from the Residue-Based Linear Free Energy Relationship Reveals a Non-Native Structure in Protein Folding

Multiprobe measurements, such as NMR and hydrogen exchange study, can provide the equilibrium constant K and kinetic rate constant k of the structural changes of a polypeptide on a per-residue basis. We previously found a linear relationship between residue-specific log K values and residue-specific log k values for the two-state topological isomerization of a 27-residue peptide. To test the general applicability of the residue-based linear free energy relationship (rbLEFR), we performed a literature search to collect residue-specific equilibrium and kinetic constants in various exchange processes, including protein folding, coupled folding and binding of intrinsically disordered peptides, and structural fluctuations of folded proteins. The good linearity in a substantial number of log-log plots proved that the rbLFER holds for the structural changes in a wide variety of protein-related phenomena. Protein molecules quickly fold into their native structures and change their conformations smoothly. Theoretical studies and molecular simulations advocate that the physicochemical basis is the consistency principle and the minimal frustration principle: Non-native structures/interactions are absent or minimized along the folding pathway. The linearity of the residue-based free energy relationship demonstrates experimentally the absence of non-native structures in transition states. In this context, the hydrogen exchange study of apomyoglobin folding intermediates is particularly interesting. We found that the residues that deviated from the linear relationship corresponded to the non-native structure, which had been identified by other experiments. The rbLFER provides a unique and practical method to probe the dynamic aspects of the transition states of protein molecules.

Maximizing Cross-Cultural Learning From Exchange Study Abroad Programs: Transformative Learning Theory

While some institutions require their students to spend a semester abroad as a prerequisite to earning a business degree, academics challenge the view that travel abroad helps students become culturally competent. Many students admit that they failed to immerse themselves in a cross-cultural environment. Therefore, the purpose of this study is to identify the components of exchange study abroad programs (ESP) that facilitate student cross-cultural learning (CCL). Building on transformative learning theory (TLT), we propose and test a conceptual model of relationships between different components of exchange programs and student CCL. The data collected from more than 700 students participating in a semester and two-semester-long programs are analyzed through logistic regression. This research contributes to the literature on the effectiveness of ESP by identifying the key components that maximize positive outcomes for students. By building on TLT, it reveals the importance of getting out of one’s comfort zone and providing students with support during the ESP. This study bears practical implications as it provides academic institutions and students with important insights that help maximize student CCL.

Second-coordination sphere effects on the reactivities of Hoveyda–Grubbs-type catalysts: a ligand exchange study using phenolic moiety-functionalized ligands

The reactivities of Hoveyda–Grubbs-type complexes are tunable through second-coordination sphere effects caused by a functional group in the ligand.