Lower Limb Knee Exoskeleton

This project is the primary phase to develop a prototype of a lower limb exoskeleton through the implementation of novel hardware and software techniques that will overcome specific issues those current exoskeletons suffer from, such as lack of robust controllability, bulkiness, and actuation performance. At this phase, a knee exoskeleton with a linear actuator has been constructed. It is controlled by using data received from electromyography (EMG) signals. Furthermore, 3D printed parts of the exoskeleton frame have been developed in order to reduce weight and for rapid prototyping. The device is to be designed as an assistive device for a non-handicapped person. The main requirement of the device is to aim more less 20% of the knee joint torque of the average human male (20-35 years) during walking. Furthermore, preliminary studies on electromechanical properties of soft robotic materials have been performed in order to explore their capabilities for this application

Brassica juncea 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase 1: expression and characterization of recombinant wild-type and mutant enzymes

3-Hydroxy-3-methylglutaryl (HMG)-CoA synthase (HMGS; EC 2.3.3.10) is the second enzyme in the cytoplasmic mevalonate pathway of isoprenoid biosynthesis, and catalyses the condensation of acetyl-CoA with acetoacetyl-CoA (AcAc-CoA) to yield S-HMG-CoA. In this study, we have first characterized in detail a plant HMGS, Brassica juncea HMGS1 (BjHMGS1), as a His(6)-tagged protein from Escherichia coli. Native gel electrophoresis analysis showed that the enzyme behaves as a homodimer with a calculated mass of 105.8 kDa. It is activated by 5 mM dithioerythreitol and is inhibited by F-244 which is specific for HMGS enzymes. It has a pH optimum of 8.5 and a temperature optimum of 35 °C, with an energy of activation of 62.5 J·mol(−1). Unlike cytosolic HMGS from chicken and cockroach, cations like Mg(2+), Mn(2+), Zn(2+) and Co(2+) did not stimulate His(6)–BjHMGS1 activity in vitro; instead all except Mg(2+) were inhibitory. His(6)–BjHMGS1 has an apparent K(m-acetyl-CoA) of 43 μM and a V(max) of 0.47 μmol·mg(−1)·min(−1), and was inhibited by one of the substrates (AcAc-CoA) and by both products (HMG-CoA and HS-CoA). Site-directed mutagenesis of conserved amino acid residues in BjHMGS1 revealed that substitutions R157A, H188N and C212S resulted in a decreased V(max), indicating some involvement of these residues in catalytic capacity. Unlike His(6)–BjHMGS1 and its soluble purified mutant derivatives, the H188N mutant did not display substrate inhibition by AcAc-CoA. Substitution S359A resulted in a 10-fold increased specific activity. Based on these kinetic analyses, we generated a novel double mutation H188N/S359A, which resulted in a 10-fold increased specific activity, but still lacking inhibition by AcAc-CoA, strongly suggesting that His-188 is involved in conferring substrate inhibition on His(6)–BjHMGS1. Substitution of an aminoacyl residue resulting in loss of substrate inhibition has never been previously reported for any HMGS