Enzymatic Depilation of Animal Hide: Identification of Elastase (LasB) from Pseudomonas aeruginosa MCM B-327 as a Depilating Protease

Conventional leather processing involving depilation of animal hide by lime and sulphide treatment generates considerable amounts of chemical waste causing severe environmental pollution. Enzymatic depilation is an environmentally friendly process and has been considered to be a viable alternative to the chemical depilation process. We isolated an extracellular protease from Pseudomonas aeruginosa strain MCM B-327 with high depilation activity using buffalo hide as a substrate. This 33 kDa protease generated a peptide mass fingerprint and de novo sequence that matched perfectly with LasB (elastase), of Pseudomonas aeruginosa. In support of this data a lasB mutant of MCM B-327 strain lacked depilatory activity and failed to produce LasB. LasB heterologously over-produced and purified from Escherichia coli also exhibited high depilating activity. Moreover, reintroduction of the lasB gene to the P. aeruginosa lasB mutant via a knock-in strategy also successfully restored depilation activity thus confirming the role of LasB as the depilating enzyme

Neuromechanical response of the upper body to unexpected perturbations during gait initiation in young and older adults

Background: Control of upper body motion deteriorates with ageing leading to impaired ability to preserve balance during gait, but little is known on the contribution of the upper body to preserve balance in response to unexpected perturbations during locomotor transitions, such as gait initiation. Aim: To investigate differences between young and older adults in the ability to modify the trunk kinematics and muscle activity following unexpected waist lateral perturbations during gait initiation. Methods: Ten young (25 ± 2 years) and ten older adults (73 ± 5 years) initiated locomotion from stance while a lateral pull was randomly applied to the pelvis. Two force plates were used to define the feet centre-of-pressure displacement. Angular displacement of the trunk in the frontal plane was obtained through motion analysis. Surface electromyography of cervical and thoracic erector spinae muscles was recorded bilaterally. Results: A lower trunk lateral bending towards the stance leg side in the preparatory phase of gait initiation was observed in older participants following perturbation. Right thoracic muscle activity was increased in response to the perturbation during the initial phase of gait initiation in young (+ 68%) but not in older participants (+ 7%). Conclusions: The age-related reduction in trunk movement could indicate a more rigid behaviour of the upper body employed by older compared to young individuals in response to unexpected perturbations preceding the initiation of stepping. Older adults’ delayed activation of thoracic muscles could suggest impaired reactive mechanisms that may potentially lead to a fall in the early stages of the gait initiation

Nafion membrane incorporated with silver nanoparticles as optical test strip for dissolved hydrogen peroxide: Preparation, deployment and the mechanism of action

We report the preparation of an optical test strip for quantitative assay of hydrogen peroxide (H2O2) in aqueous solution. Silver nanoparticles(AgNPs) with good optical quality are synthesized by in-situ reduction of silver ions in Nafion-117 membrane previously absorbed with ascorbate ion (HA(-)). The nanocomposite membrane exhibits a narrow Localized Surface Plasmon Resonance (LSPR) band at 413 nm. The extent of decrease in intensity of the LSPR band in presence of H2O2 solution gives quantitative estimate of H2O2 concentration. The detector has been found to show a good analytical response towards H2O2 detection at pH 7 over a wide concentration range. The detection limit has been calculated to be 2.6 x 10(-8) mol L-1, which is lower than the conventional enzyme based biosensors. The present test strip has been succesfully employed for the quantitative assay of H2O2 in milk. The mechanism of change in LSPR in presence of H2O2 (1.0 x 10(-3) mol L-1) has been explored for the first time using time resolved Small-Angle X-ray Scattering and radiotracer techniques. The results show that at this concentration of H2O2, its sharp oxidative sawing action is responsible for cutting off the nanoparticles into smaller fragments resulting in rapid reduction of absorption crossection. (C) 2017 Elsevier B.V. All rights reserved