Local and Large-Scale Conformational Dynamics in Unfolded Proteins and IDPs. I. Effect of Solvent Viscosity and Macromolecular Crowding.

Protein/solvent interactions largely influence protein dynamics, particularly motions in unfolded and intrinsically disordered proteins (IDPs). Here, we apply triplet-triplet energy transfer (TTET) to investigate the coupling of internal protein motions to solvent motions by determining the effect of solvent viscosity (η) and macromolecular crowding on the rate constants of loop formation () in several unfolded polypeptide chains including IDPs. The results show that the viscosity dependence of loop formation depends on amino acid sequence, loop length, and co-solute size.

Local and Large-Scale Conformational Dynamics in Unfolded Proteins and IDPs. II. Effect of Temperature and Internal Friction.

Internal dynamics of proteins are essential for protein folding and function. Dynamics in unfolded proteins are of particular interest since they are the basis for many cellular processes like folding, misfolding, aggregation, and amyloid formation and also determine the properties of intrinsically disordered proteins (IDPs). It is still an open question of what governs motions in unfolded proteins and whether they encounter major energy barriers.

Will the Use of Intraoperative Liposomal Bupivacaine During Thumb Carpometacarpal Arthroplasty Decrease Postoperative Use of Opioids? A Prospective Randomized Study.

Purpose: This study evaluated the use of intraoperative local injection of liposomal bupivacaine to decrease opioid use in the early postoperative period for patients undergoing outpatient thumb carpometacarpal joint arthroplasty.

Methods: A prospective, randomized, controlled, single-blinded study was designed to compare 2 groups of patients for opioid use, pain scores, and nonopioid pill consumption within 5 days after surgery. The investigational group received an intraoperative injection of 10 ml (133 mg) liposomal bupivacaine.

Automated Reporting of Patient Outcomes in Hand Surgery: A Pilot Study.

Background: Obtaining patient-reported outcomes (PROs) is becoming a standard component of patient care. For nonacademic practices, this can be challenging. From this perspective, we designed a nearly autonomous patient outcomes reporting system.

Atypical Mycobacterial Infections of the Upper Extremity.

Atypical mycobacterial infections of upper extremity synovial-lined structures are often misdiagnosed and unrecognized. Despite an increasing incidence, lack of physician awareness of these pathogens may result in considerable delay in diagnosis and management, potentially leading to permanent disability. The authors conducted a literature review and analyzed 31 cases of penetrating atypical mycobacterial infection to better understand the clinical characteristics and to evaluate their posttreatment complication rate compared with available literature.

Hardware-related complications following radiocarpal arthrodesis using a dorsal plate.

Background Hardware-related complications more than 6 months after total wrist arthrodesis are rarely reported, and controversy remains around the inclusion of the middle finger carpometacarpal joint (CMCJ) in the fusion mass. Purpose To determine the frequency of hardware-related complications including plate fractures, screw fractures, and symptomatic plate/screw loosening, and to investigate whether failure to fuse the middle finger CMCJ contributed to these hardware complications. Patients and Methods A retrospective chart review was designed to identify long-term hardware-related complications following 122 wrist arthrodeses using plate fixation.

Redefining the dry molten globule state of proteins.

Dynamics and function of proteins are governed by the structural and energetic properties of the different states they adopt and the barriers separating them. In earlier work, native-state triplet-triplet energy transfer (TTET) on the villin headpiece subdomain (HP35) revealed an equilibrium between a locked native state and an unlocked native state, which are structurally similar but have different dynamic properties. The locked state is restricted to low amplitude motions, whereas the unlocked state shows increased conformational flexibility and undergoes local unfolding reactions.

Splintage in the treatment of sagittal band incompetence and extensor tendon subluxation.

Unlabelled: This study assessed the success of splintage for traumatic and atraumatic sagittal band incompetence and its relationship to the duration of symptoms before treatment. A retrospective review of all patients with sagittal band incompetence treated with splintage was performed. All patients had extensor tendon subluxation on physical examination.

Transition state and ground state properties of the helix-coil transition in peptides deduced from high-pressure studies.

Volume changes associated with protein folding reactions contain valuable information about the folding mechanism and the nature of the transition state. However, meaningful interpretation of such data requires that overall volume changes be deconvoluted into individual contributions from different structural components. Here we focus on one type of structural element, the α-helix, and measure triplet-triplet energy transfer at high pressure to determine volume changes associated with the helix-coil transition.

Testing the diffusing boundary model for the helix-coil transition in peptides.

The dynamics of peptide α-helices have been studied extensively for many years, and the kinetic mechanism of the helix-coil dynamics has been discussed controversially. Recent experimental results have suggested that equilibrium helix-coil dynamics are governed by movement of the helix/coil boundary along the peptide chain, which leads to slower unfolding kinetics in the helix center compared with the helix ends and position-independent helix formation kinetics. We tested this diffusion of boundary model in helical peptides of different lengths by triplet-triplet energy transfer measurements and compared the data with simulations based on a kinetic linear Ising model.

Proximal row carpectomy: minimum 20-year follow-up.

Purpose: Proximal row carpectomy (PRC) is a motion-sparing procedure for degenerative disorders of the proximal carpal row. Reported results at a minimum 10-year follow-up consistently show maintenance of strength, motion, and satisfaction with an average conversion rate to radiocarpal arthrodesis of 12%. We hypothesized that PRC would continue to provide a high level of satisfaction and function at a minimum of 20 years.

Following the energy transfer in and out of a polyproline-peptide.

The intramolecular and intermolecular vibrational energy flow in a polyproline peptide with a total number of nine amino acids in the solvent dimethyl sulfoxide is investigated using time-resolved infrared (IR) spectroscopy. Azobenzene covalently bound to a proline sequence containing nitrophenylalanine as a local sensor for vibrational excess energy serves as a heat source. Information on through-space distances in the polyproline peptides is obtained by independent Förster resonance energy transfer measurements.

Percutaneous pinning of fractures in the proximal third of the proximal phalanx: complications and outcomes.

Purpose: Two common techniques for fixation of extra-articular fractures at the proximal phalanx base are transarticular (across the metacarpophalangeal joint) and extra-articular cross-pinning. The aim of this study was to assess the complications and outcomes of these 2 techniques. Our hypothesis was that transarticular and extra-articular closed reduction and percutaneous pinning of base of proximal phalanx fractures have similar complication rates and outcomes.

Dynamics and mechanisms of coupled protein folding and binding reactions.

Protein folding coupled to binding of a specific ligand is frequently observed in biological processes. In recent years numerous studies have addressed the structural properties of the unfolded proteins in the absence of their ligands. Surprisingly few time-resolved investigations on coupled folding and binding reactions have been published up to date and the dynamics and kinetic mechanisms of these processes are still only poorly understood.

Mapping backbone and side-chain interactions in the transition state of a coupled protein folding and binding reaction.

Understanding the mechanism of protein folding requires a detailed knowledge of the structural properties of the barriers separating unfolded from native conformations. The S-peptide from ribonuclease S forms its α-helical structure only upon binding to the folded S-protein. We characterized the transition state for this binding-induced folding reaction at high resolution by determining the effect of site-specific backbone thioxylation and side-chain modifications on the kinetics and thermodynamics of the reaction, which allows us to monitor formation of backbone hydrogen bonds and side-chain interactions in the transition state.

Individual finger sensibility in carpal tunnel syndrome.

Purpose: Sensibility testing plays a role in the diagnosis of carpal tunnel syndrome (CTS). No single physical examination test has proven to be of critical value in the diagnosis, especially when compared with electrodiagnostic testing (EDX). The purpose of this study was to define which digits are most affected by CTS, both subjectively and with objective sensibility testing.

An unlocking/relocking barrier in conformational fluctuations of villin headpiece subdomain.

A reversible structural unlocking reaction, in which the close-packed van der Waals interactions break cooperatively, has been found for the villin headpiece subdomain (HP35) using triplet-triplet-energy transfer to monitor conformational fluctuations from equilibrium. Unlocking is associated with an unfavorable enthalpy change (DeltaH(0) = 35 +/- 4 kJ/mol) which is nearly compensated in free energy by the entropy change (DeltaS(0) = 112 +/- 20 Jxmol(-1)xK(-1)). The unlocking reaction has a time constant of about 1 mus at 5 degrees C and is enthalpy-limited with an activation energy of 32 +/- 1 kJ/mol and a large Arrhenius preexponential factor of A = 7.

Hemi-hamate arthroplasty provides functional reconstruction of acute and chronic proximal interphalangeal fracture-dislocations.

Purpose: Hemi-hamate resurfacing arthroplasty is a treatment alternative for the management of severe acute and chronic dorsal proximal interphalangeal (PIP) fracture-dislocations. This study was designed to determine whether this procedure would successfully restore function after such injuries.

Methods: Hemi-hamate reconstructions were performed on 33 patients (mean age, 34 years) who presented to 1 hand surgery practice with dorsal PIP fracture-dislocations.

NMR structure of a monomeric intermediate on the evolutionarily optimized assembly pathway of a small trimerization domain.

Efficient formation of specific intermolecular interactions is essential for self-assembly of biological structures. The foldon domain is an evolutionarily optimized trimerization module required for assembly of the large, trimeric structural protein fibritin from phage T4. Monomers consisting of the 27 amino acids comprising a single foldon domain subunit spontaneously form a natively folded trimer.

Local conformational dynamics in alpha-helices measured by fast triplet transfer.

Coupling fast triplet-triplet energy transfer (TTET) between xanthone and naphthylalanine to the helix-coil equilibrium in alanine-based peptides allowed the observation of local equilibrium fluctuations in alpha-helices on the nanoseconds to microseconds time scale. The experiments revealed faster helix unfolding in the terminal regions compared with the central parts of the helix with time constants varying from 250 ns to 1.4 micros at 5 degrees C.

Effect of thioxopeptide bonds on alpha-helix structure and stability.

Thioxoamide (thioamide) bonds are nearly isosteric substitutions for amides but have altered hydrogen-bonding and photophysical properties. They are thus well-suited backbone modifications for physicochemical studies on peptides and proteins. The effect of thioxoamides on protein structure and stability has not been subject to detailed experimental investigations up to date.

Conserved folding pathways of alpha-lactalbumin and lysozyme revealed by kinetic CD, fluorescence, NMR, and interrupted refolding experiments.

In this report, it is shown by a combination of stopped-flow CD, fluorescence, and time-resolved NMR studies that the Ca(2+)-induced refolding of bovine alpha-lactalbumin (BLA) at constant denaturant concentration (4 M urea) exhibits triple-exponential kinetics. In order to distinguish between parallel folding pathways and a strictly sequential formation of the native state, interrupted refolding experiments were conducted. We show here that the Ca(2+)-induced refolding of BLA involves parallel pathways and the transient formation of a folding intermediate on the millisecond timescale.

A nearly isosteric photosensitive amide-backbone substitution allows enzyme activity switching in ribonuclease s.

psi[CS-NH]4-RNase S, a site specific modified version of RNase S obtained by thioxylation (O/S exchange) at the Ala4-Ala5- peptide bond, was used to evaluate the impact of protein backbone photoswitching on bioactivity. psi[CS-NH](4)-RNase S was yielded by recombination of the S-protein and the respective chemically synthesized thioxylated S-peptide derivative. Comparison with RNase S revealed similar thermodynamic stability of the complex and an unperturbed enzymatic activity toward cytidine 2',3'-cyclic monophosphate (cCMP).