CO Release from N,C,S-Pincer Iron(III) Carbonyl Complexes Induced by Visible-to-NIR Light Irradiation: Mechanistic Insight into Effects of Axial Phosphorus Ligands

Light-induced CO release from newly synthesized N,C,S-pincer iron­(III) carbonyl complexes with two phosphorus ligands<i>trans</i>-[Fe­(L-κ³<i>N,C,S</i>)­(CO)­(PR₂R′)₂]­PF₆ ([<b>1</b>]­PF₆, R = Me, R′ = Ph; [<b>2</b>]­PF₆, R = R′ = Me; [<b>3</b>]­PF₆, R = R′ = OEt)were investigated. All the iron­(III) carbonyl complexes were stable in solution and showed light-inducible CO release under ambient conditions. Studies on the wavelength dependence of photoreaction revealed that the phosphite complex [<b>3</b>]­PF₆ exhibited the most extended photosensitivity including all visible and a part of near-IR light (390–800 nm wavelengths). The phosphine complexes [<b>1</b>]­PF₆ and [<b>2</b>]­PF₆ showed sensitivity to only the higher-energy region of visible light (390–450 nm). Quantum-chemical calculations and spectroscopic data suggested that all complexes [<b>1</b>]­PF₆–[<b>3</b>]­PF₆ have dπ–dπ excitation modes to depopulate Fe–C­(carbonyl) bonding and potentially induce the CO release by irradiation of light in the near-IR region, although moderately weakened Fe–C­(carbonyl) bonding due to stronger π-backbonding by the phosphite ligand rendered the excitation effective on the CO release exclusively in [<b>3</b>]­PF₆

Preferences Regarding Shared Decision-Making in Japanese Inflammatory Bowel Disease Patients

<p><strong>Article full text</strong></p> <p><br> The full text of this article can be found <a href="https://link.springer.com/article/10.1007/s12325-016-0436-0"><b>here</b>.</a><br> <br> <strong>Provide enhanced digital features for this article</strong><br> If you are an author of this publication and would like to provide additional enhanced digital features for your article then please contact <u>[email protected]</u>.<br> <br> The journal offers a range of additional features designed to increase visibility and readership. All features will be thoroughly peer reviewed to ensure the content is of the highest scientific standard and all features are marked as ‘peer reviewed’ to ensure readers are aware that the content has been reviewed to the same level as the articles they are being presented alongside. Moreover, all sponsorship and disclosure information is included to provide complete transparency and adherence to good publication practices. This ensures that however the content is reached the reader has a full understanding of its origin. No fees are charged for hosting additional open access content.<br> <br> Other enhanced features include, but are not limited to:<br> • Slide decks<br> • Videos and animations<br> • Audio abstracts<br> • Audio slides<u></u></p

Thermodynamic Effects of the Alteration of the Axial Ligand on the Unfolding of Thermostable Cytochrome <i>c</i>

The role the axial methionine plays in the conformational properties and thermostability of the heme active site has been investigated with the help of site-specific mutations at the axial Met69 position with His (M69H) and Ala (M69A) in thermostable cytochrome <i>c</i>₅₅₂ from <i>Thermus thermophilus</i>. Detailed circular dichroism, direct electrochemistry, and other spectroscopic studies have been employed to investigate the thermally induced and GdnHCl-induced unfolding properties of the heme active site of the wild type and the mutants of cytochrome <i>c</i>₅₅₂. We observed an unusually high thermodynamic and thermal stability of the M69A mutant compared to that of wild-type cytochrome <i>c</i>₅₅₂. However, the M69H mutant exhibited a slightly lower unfolding free energy compared to that of the wild-type protein. The high conformational stability of the M69A mutant was attributed to the presence of residual structure in the unfolded state as well as to the altered conformation in the folded state of this mutant of cytochrome <i>c</i>₅₅₂. This study thus supports the view that apart from the folded state, the unfolded state of a protein may also make a significant contribution to the stability of a protein

Cytochrome <i>c</i>₅₅₂ from <i>Thermus thermophilus</i> Engineered for Facile Substitution of Prosthetic Group

The facile replacement of heme <i>c</i> in cytochromes <i>c</i> with non-natural prosthetic groups has been difficult to achieve due to two thioether linkages between cysteine residues and the heme. Fee et al. demonstrated that cytochrome <i>c</i>₅₅₂ from <i>Thermus thermophilus</i>, overproduced in the cytosol of <i>E. coli</i>, has a covalent linkage cleavable by heat between the heme and Cys11, as well as possessing the thioether linkage with Cys14 [Fee, J. A. (2004) <i>Biochemistry 43</i>, 12162–12176]. Prompted by this result, we prepared a C14A mutant, anticipating that the heme species in the mutant was bound to the polypeptide solely through the thermally cleavable linkage; therefore, the removal of the heme would be feasible after heating the protein. Contrary to this expectation, C14A immediately after purification (as-purified C14A) possessed no covalent linkage. An attempt to extract the heme using a conventional acid–butanone method was unsuccessful due to rapid linkage formation between the heme and polypeptide. Spectroscopic analyses suggested that the as-purified C14A possessed a heme <i>b</i> derivative where one of two peripheral vinyl groups had been replaced with a group containing a reactive carbonyl. A reaction of the as-purified C14A with [BH₃CN]⁻ blocked the linkage formation on the carbonyl group, allowing a quantitative yield of heme-free apo-C14A. Reconstitution of apo-C14A was achieved with ferric and ferrous heme <i>b</i> and zinc protoporphyrin. All reconstituted C14As showed spontaneous covalent linkage formation. We propose that C14A is a potential source for the facile production of an artificial cytochrome <i>c</i>, containing a non-natural prosthetic group

Severity and Diurnal Improvement of Morning Stiffness Independently Associate with Tenosynovitis in Patients with Rheumatoid Arthritis

<div><p>Background and objectives</p><p>Although morning stiffness has long been recognized as a characteristic feature of rheumatoid arthritis (RA), it is no more included in the 2010 ACR/EULAR Classification Criteria or in the current major instruments for evaluating disease activity of RA. In this cross-sectional study, we aimed to determine the independent value and the optimal measurement of morning stiffness by clarifying the associations between morning stiffness and synovial inflammation.</p><p>Patients and methods</p><p>We enrolled 76 consecutive RA patients who underwent musculoskeletal ultrasound examination and agreed to participate in the study. In addition to asking the duration of morning stiffness, we asked patients to complete a diagram which represents the time course of their morning stiffness in the dominant hand. Based on this diagram, we calculated the severity and the diurnal improvement of morning stiffness. We also determined the activity of intra-articular synovitis in 11 joints and tenosynovitis in 8 tendons/tendon compartments in the same hand by using power Doppler (PD) ultrasound with a semiquantitative score (0–3).</p><p>Results</p><p>For intra-articular synovitis, swollen/tender joint counts more strongly correlated with total PD scores (ρ = 0.379–0.561, p ≤ 0.001) than did any parameters of morning stiffness (ρ = 0.217–0.314, p = 0.006–0.021). For tenosynovitis, however, the severity on awakening and the improvement of morning stiffness more strongly correlated with total PD scores (ρ = 0.503–0.561, p < 0.001) than did swollen/tender joint counts (ρ = 0.276–0.388, p = 0.001–0.016). Multivariate analyses identified the severity on awakening and the improvement but not the duration of morning stiffness as factors that independently associate with the total tenosynovial PD score.</p><p>Conclusions</p><p>Our data demonstrate a pathophysiological link between morning stiffness and tenosynovitis and also give an insight into the optimal measurement of morning stiffness. Our data support an independent value of evaluating morning stiffness in the management of RA.</p></div

Multivariate linear regression models to identify factors which independently associate with power Doppler scores.

<p>Multivariate linear regression models to identify factors which independently associate with power Doppler scores.</p

Local clinical manifestations and ultrasound scores in dominant hand.

<p>Local clinical manifestations and ultrasound scores in dominant hand.</p

Prevalence of power Doppler signals in each joint/tendon region.

<p>Prevalence of each power Doppler (PD) grade > 0 in each joint (A) and each tendon region (B). IP, interphalangeal joint; PIP, proximal interphalangeal joint; MCP, metacarpo-phalangeal joint; FD, flexor digitorum; Wrist Ext, wrist extensor tendons.</p

An example diagram for time course of morning stiffness in dominant hand.

<p>(1) Severity of stiffness on awakening, (2) Severity of stiffness at the first 1/4 of total awake time, (3) Improvement of stiffness at the first 1/4 of total awake time, (4) Severity of stiffness at the first 1/2 of total awake time, (5) Improvement of stiffness at the first 1/2 of total awake time, (6) Severity of stiffness at bed time, (7) Improvement of stiffness at bed time.</p

Patients’ characteristics, current treatment, and disease activity.

<p>Patients’ characteristics, current treatment, and disease activity.</p