https://vital.seals.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:45268 Wed 16 Mar 2022 10:18:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4102 Wed 12 May 2021 23:39:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30590 Wed 12 May 2021 23:10:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:37082 Wed 12 May 2021 20:49:43 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4557 Wed 12 May 2021 20:17:39 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:37153 Wed 12 May 2021 20:17:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4285 Wed 12 May 2021 19:56:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:29926 Wed 12 May 2021 19:50:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:29928 Wed 12 May 2021 19:14:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:29116 Wed 12 May 2021 19:14:06 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4538 Wed 12 May 2021 19:02:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4548 Wed 12 May 2021 18:32:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:29118 Wed 12 May 2021 18:23:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4537 Wed 12 May 2021 17:56:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4149 Wed 12 May 2021 17:35:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4331 Wed 12 May 2021 17:29:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4293 Wed 12 May 2021 17:24:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:11330 Wed 12 May 2021 17:13:03 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:41337 Wed 12 May 2021 15:02:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:42174 Wed 12 May 2021 15:00:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:41377 Wed 12 May 2021 14:34:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:41484 Wed 12 May 2021 14:28:57 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:41163 Wed 12 May 2021 13:49:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:62598 Thu 16 Mar 2023 11:26:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:29119 Thu 13 May 2021 16:04:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30589 50Îll viability at concentrations≤ 160μg/mL, however the conjugates showed<50% cell viabilityatconcentrations≤ 160μg/mLprobably due to the enhanced singlet oxygen quantum yield. The findings from this work show the importance of linking photosensitises such as phthalocyanines to metal nanoparticles for the enhancement ofsinglet oxygen quantum yield and ultimately the photodynamic effect.]]> Thu 13 May 2021 08:10:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4287 0.99. In the column experiment the highest loading capacity of Pt and Pd were 7.4 mg/g and 4.3 mg/g respectively on the nanofiber sorbent material based on ethylenediamine (EDA). The polystyrene and silica-based resins with triethylenetetramine (TETA) functionality (M-TETA and S-TETA) showed selectivity for platinum and palladium, respectively. Metal chlorido complexes loaded on the sorbent materials were recovered by using 3% m/v thiourea solution as teh eluting agent with quantitative desorption efficiency under the selected experimental conditions. The separation of platinum from palladium was partially achieved by selective stripping of PtCl₆²⁻ with 0.5 M of NaClO₄ in 1.0 M HCI with PdCl₄²⁻ was eluted with 0.5 M thiourea in 1.0 M HCI. The selectivity of the M-TETA and S-TETA sorbent materials was proved by column separation of platinum(IV) and palladium(II), respectively, from synthetic solutions containing iridium(IV) and rhodium(III). The loading capacity for platinum on M-TETA was 0.09 mg/g while it was 0.27 mg/g for palladium on S-TETA.]]> Thu 13 May 2021 07:36:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4541 Thu 13 May 2021 07:06:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:35406 Thu 13 May 2021 06:50:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4150 Thu 13 May 2021 06:17:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3965 1 mM resulted in the precipitation of protein-nanoparticle bioconjugates, due to unfavourable acidic conditions. This demonstrated that the nanoparticles were binding to and becoming stabilised by general protein in the cell-free solution. Upon addition of a sodium-bicarbonate buffer, a general increase in Pt(IV) reduction to Pt(II) was observed. The addition of the buffer also resulted in an unexplained change in particle morphology and for this reason was not used in subsequent investigations. Polyvinylpyrrolidone (PVP) was shown to compromise the reduction rate of the Pt(IV) ion by SRB cells. The presence of extracellular NP’s was suggested by the colour of the supernatant turning brown and the A334 increasing over time. Attempts to visualise the particles by transmission electron microscopy (TEM) resulted in an unexpected phenomenon where nanoparticles could be observed to form dynamically upon irradiation by the electron beam. Extended irradiation by the electron beam also resulted in structural changes of the particles occurring during observation. An increase in temperature was shown to increase the reduction rate which in turn resulted in particles decreasing in size. The starting pH was shown to have a significant effect on the reduction rate and particle morphology although specific trends could not be identified. In conclusion, the cell-soluble extract from the sulfate-reducing consortium investigated, is capable of Pt(0) nanoparticle synthesis. Precise control over the particle morphology was not attained although the mechanism was further clarified and optimal conditions for nanoparticle synthesis were determined.]]> Thu 13 May 2021 06:12:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4539 Thu 13 May 2021 04:42:43 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4169 Thu 13 May 2021 04:27:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10555 Thu 13 May 2021 03:51:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3923 Thu 13 May 2021 02:31:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4168 Thu 13 May 2021 02:23:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4291 Thu 13 May 2021 01:46:25 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4500 Thu 13 May 2021 01:23:39 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4334 Thu 13 May 2021 01:17:13 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34528 Thu 13 May 2021 00:32:13 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:46417 Thu 10 Feb 2022 10:51:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28063 90%) sequence similarity between BSCOMT and human soluble COMT (HSCOMT). BSCOMT was partially purified to 7.78 fold, 1.65% yield and had a specific activity of 0.052 U/mg. It had pH and temperature optima of 8.5 and 40oC, respectively. The Km, Vmax, Kcat and Kcat/Km towards esculetin methylation were respectively 1.475±0.130 pM, 0.0353±0.001 pmol/ml/min, 1.748 x 10-2±5.0x10-4 min-1 and 1.18x10-2 M-1. min-1. HSCOMT was expressed in Escherichia coli BL21(DE3) which showed optimal activity for esculetin methylation at pH and temperature of 7.0 and 30°C, respectively. It was purified to 5.62 fold, 22.6% yield with a specific activity of 3.85 U/mg. HSCOMT kinetic plots, upon incubation of the reaction mixture at 30°C for 5 min before addition of SAM was hyperbolic with Km, Vmax, Kcat and Kcat/Km values of 1.79 pM, 0.412 pmol/ml/min, 2.08 min-1 and 1.165 M-1. min-1, respectively. AuNPs and AgNPs showed a concentration dependent inhibition of HSCOMT activity upon increasing the 5 min incubation time to 1 h. Interestingly, HSCOMT kinetics, with 1 h incubation at 30°C, showed a sigmoidal curve, as well as increased activity. Incubation of the reaction mixture in the presence of 60 pM AuNPs and/or AgNPs for 1 hreversed the observed sigmoidal to a hyperbolic curve, with kinetic parameters comparable to those of 5 min incubation. SDS-PAGE analyses of HSCOMT after the kinetic experiments showed the enzyme incubated for 5 min as a monomer, while that which was incubated for 1 h migrated substantially as dimer. However, the HSCOMT incubated for 1 h in the presence of 60 pM AuNPs and/or AgNPs migrated as a monomer. This indicated that the extension of the incubation period allowed the dimerization of HSCOMT, which exhibited sigmoidal kinetics and higher activity. The presence of NPs impeded the HSCOMT dimerization which decreased the activity. Varying the concentration of SAM suggested that SAM had an allosteric modulatory effect on HSCOMT. Absorption spectroscopy indicated adsorption of HSCOMT on the gold and silver NP surfaces and the formation of NPs-HSCOMT corona. Fluorescence spectroscopy showed that the interaction of HSCOMT with both gold and silver NPs was governed by a static quenching mechanism, implying the formation of a non-fluorescent fluorophore-NP complex at the ground state. Further fluorometric analyses indicated that both gold and silver NPs had contact with Trp143; that the interactions were spontaneous and were driven by electrostatic interactions. Fourier transform infrared spectroscopic studies showed the adsorption of HSCOMT of the NPs surfaces to cause relaxation of the enzyme’s B-sheet structures. Molecular docking studies indicated involvement of largely hydrophilic amino acids, with the interacting distances of less than 3.5A. These findings signify the potential of nanotechnology in the control of COMT catalytic activity for the management of the COMT-related disorders.]]> Mon 13 Mar 2023 14:31:23 SAST ]]>