The Energy Landscape, Folding Pathways and the Kinetics of a Knotted Protein

The folding pathway and rate coefficients of the folding of a knotted protein are calculated for a potential energy function with minimal energetic frustration. A kinetic transition network is constructed using the discrete path sampling approach, and the resulting potential energy surface is visualized by constructing disconnectivity graphs. Owing to topological constraints, the low-lying portion of the landscape consists of three distinct regions, corresponding to the native knotted state and to configurations where either the N- or C-terminus is not yet folded into the knot. The fastest folding pathways from denatured states exhibit early formation of the N-terminus portion of the knot and a rate-determining step where the C-terminus is incorporated. The low-lying minima with the N-terminus knotted and the C-terminus free therefore constitute an off-pathway intermediate for this model. The insertion of both the N- and C-termini into the knot occur late in the folding process, creating large energy barriers that are the rate limiting steps in the folding process. When compared to other protein folding proteins of a similar length, this system folds over six orders of magnitude more slowly.Comment: 19 page

Mechanical Bonds and Topological Effects in Radical Dimer Stabilization

While mechanical bonding stabilizes tetrathiafulvalene (TTF) radical dimers, the question arises: what role does topology play in catenanes containing TTF units? Here, we report how topology, together with mechanical bonding, in isomeric [3]- and doubly interlocked [2]catenanes controls the formation of TTF radical dimers within their structural frameworks, including a ring-in-ring complex (formed between an organoplatinum square and a {2+2} macrocyclic polyether containing two 1,5-dioxynaphthalene (DNP) and two TTF units) that is topologically isomeric with the doubly interlocked [2]catenane. The separate TTF units in the two {1+1} macrocycles (each containing also one DNP unit) of the isomeric [3]catenane exhibit slightly different redox properties compared with those in the {2+2} macrocycle present in the [2]catenane, while comparison with its topological isomer reveals substantially different redox behavior. Although the stabilities of the mixed-valence (TTF2)^(•+) dimers are similar in the two catenanes, the radical cationic (TTF^(•+))_2 dimer in the [2]catenane occurs only fleetingly compared with its prominent existence in the [3]catenane, while both dimers are absent altogether in the ring-in-ring complex. The electrochemical behavior of these three radically configurable isomers demonstrates that a fundamental relationship exists between topology and redox properties

Assessment of the level of performance and impact of motivation on teachers at colleges of nursing and midwifery in Borno and Yobe States, Nigeria

Background: Employees’ satisfaction and motivation are major drivers of job productivity, especially among teachers of healthcare providers such as nurses and midwives. Objective of study: To determine factors that influence teachers’ motivation in Colleges of Nursing and Midwifery in Borno and Yobe states of Nigeria. Specifically, to assess the level of teachers’ motivation and their relationship with the performance of the teachers in the selected colleges. Materials and methods: This descriptive and quantitative questionnaire-based survey randomly (stratified) selected 120 participants (teachers) from the selected colleges. Multidimensional Work Motivation Scale (MWMS) was used to assess the level and employees’ work motivation based on their psychological responses to different personal and organizational factors in the work situation and environment. Data were analysed using Statistical Package for Social Science Version 23.0. Results: Of all the study participants, 64 (54%) were males. Also, 77% of them were married while only 7% were single. Those between 36-40 years made the highest, 49 (41%) while those < 27 years were the least, 1 (1%). The majority of them, 85 (70%) had a bachelor’s degree, but a few, 3 (2%) had obtained a doctorate. Those with 6-10 years of teaching experience made the highest (34%). Of all the analyses made, the influence of infrastructure had the highest MWMS mean ± SD (29.22 ± 3.66), followed by the effects of Monetary rewards (26.77 ± 4.33), and the least was the influence of operational facilities (17.64 ± 2.81). The result of the study revealed that the level of staff performance in the study areas was relatively high, and the level of staff motivation was low. Conclusion: Based on the findings, prompt teacher promotion, lucrative payment and job satisfaction are the principal factors guiding the mind and perception of teachers as a vehicle for transmitting, generating and enhancing teacher’s job performance in selected colleges