Second-Sphere Histidine Catalytic Function in a Fungal Polysaccharide Monooxygenase.

Fungal polysaccharide monooxygenases (PMOs) oxidatively degrade cellulose and other carbohydrate polymers via a mononuclear copper active site using either O or HO as a cosubstrate. Cellulose-active fungal PMOs in the auxiliary activity 9 (AA9) family have a conserved second-sphere hydrogen-bonding network consisting of histidine, glutamine, and tyrosine residues. The second-sphere histidine has been hypothesized to play a role in proton transfer in the O-dependent PMO reaction.

Role of the Coiled-Coil Domain in Allosteric Activity Regulation in Soluble Guanylate Cyclase.

Soluble guanylate cyclase (sGC) is the primary nitric oxide (NO) receptor in higher eukaryotes, including humans. NO-dependent signaling via sGC is associated with important physiological effects in the vascular, pulmonary, and neurological systems, and sGC itself is an established drug target for the treatment of pulmonary hypertension due to its central role in vasodilation. Despite isolation in the late 1970s, high-resolution structural information on full-length sGC remained elusive until recent cryo-electron microscopy structures were determined of the protein in both the basal unactivated state and the NO-activated state.

Closed Suction Drainage after Total Knee Arthroplasty with Concomitant Intravenous Tranexamic Acid Administration.

Drain use in total knee arthroplasty (TKA) remains controversial. Use has been associated with increased complications, particularly postoperative transfusion, infection, increased cost, and longer hospital stays. However, studies examining drain use were performed before widespread adoption of tranexamic acid (TXA), which markedly reduces transfusion without increasing venous thromboembolism events.

Characterization of a unique polysaccharide monooxygenase from the plant pathogen .

Blast disease in cereal plants is caused by the fungus and accounts for a significant loss in food crops. At the outset of infection, expression of a putative polysaccharide monooxygenase (PMO9A) is increased. PMO9A contains a catalytic domain predicted to act on cellulose and a carbohydrate-binding domain that binds chitin.

Batter's Shoulder: Clinical Outcomes and Return to Sport.

Background Batter's shoulder has been defined as an acute posterior subluxation of the lead shoulder during a baseball swing causing a traumatic tear of the posterior labrum. There are limited data correlating repair techniques with return-to-play information but none utilizing standardized outcome measures. The purpose of this study is to examine a case series of patients for postoperative return-to-play and obtain follow-up using standardized outcome measures.

Total hip replacement failure due to adverse local tissue reaction from both ceramic abrasive wear and trunnion corrosion.

The most common sources for metal ions after total hip arthroplasty (THA) are the bearing surface in metal-on-metal articulations and trunnion corrosion. Concomitant dual interface failure is an uncommon complication in metal-on-polyethylene THA. We report an unusual case of a 59-year-old woman with ceramic-on-ceramic THA in 2005, who underwent revision to metal-on-polyethylene THA 4 years later after femoral head fracture.

Convergent allostery in ribonucleotide reductase.

Ribonucleotide reductases (RNRs) use a conserved radical-based mechanism to catalyze the conversion of ribonucleotides to deoxyribonucleotides. Within the RNR family, class Ib RNRs are notable for being largely restricted to bacteria, including many pathogens, and for lacking an evolutionarily mobile ATP-cone domain that allosterically controls overall activity. In this study, we report the emergence of a distinct and unexpected mechanism of activity regulation in the sole RNR of the model organism Bacillus subtilis.

An endogenous dAMP ligand in class Ib RNR promotes assembly of a noncanonical dimer for regulation by dATP.

The high fidelity of DNA replication and repair is attributable, in part, to the allosteric regulation of ribonucleotide reductases (RNRs) that maintains proper deoxynucleotide pool sizes and ratios in vivo. In class Ia RNRs, ATP (stimulatory) and dATP (inhibitory) regulate activity by binding to the ATP-cone domain at the N terminus of the large α subunit and altering the enzyme's quaternary structure. Class Ib RNRs, in contrast, have a partial cone domain and have generally been found to be insensitive to dATP inhibition.

Transient Thermal Response of a Guarded-Hot-Plate Apparatus for Operation Over an Extended Temperature Range.

A mathematical model is presented for a new-generation guarded-hot-plate apparatus to measure the thermal conductivity of insulation materials. This apparatus will be used to provide standard reference materials for greater ranges of temperature and pressure than have been previously available. The apparatus requires precise control of 16 interacting heated components to achieve the steady temperature and one-dimensional heat-transfer conditions specified in standardized test methods.

X-ray Scattering Studies of Protein Structural Dynamics.

X-ray scattering is uniquely suited to the study of disordered systems and thus has the potential to provide insight into dynamic processes where diffraction methods fail. In particular, while X-ray crystallography has been a staple of structural biology for more than half a century and will continue to remain so, a major limitation of this technique has been the lack of dynamic information. Solution X-ray scattering has become an invaluable tool in structural and mechanistic studies of biological macromolecules where large conformational changes are involved.

Gas Phase Oxidation of Campholenic Aldehyde and Solution Phase Reactivity of its Epoxide Derivative.

The rate constant for the OH reaction with campholenic aldehyde (CA) was measured using the flow tube-chemical ionization mass spectrometry method with a relative rate kinetics technique and was found to be (6.54 ± 0.52) × 10 cm molecule s at 100 Torr pressure and 298 K.

Thermal response simulation for tuning PID controllers in a 1016 mm guarded hot plate apparatus.

A mathematical model has been developed and used to simulate the controlled thermal performance of a large guarded hot-plate apparatus. This highly specialized apparatus comprises three interdependent components whose temperatures are closely controlled in order to measure the thermal conductivity of insulation materials. The simulation model was used to investigate control strategies and derive controller gain parameters that are directly transferable to the actual instrument.