1.
Gustavsson, Martin, 1984-, et al.
(author)
Surface Expression of omega-Transaminase in Escherichia coli
2014
In: Applied and Environmental Microbiology. - : American Society for Microbiology. - 0099-2240 .- 1098-5336. ; 80:7, s. 2293-2298
Journal article (peer-reviewed) abstract
Chiral amines are important for the chemical and pharmaceutical industries, and there is rapidly growing interest to use transaminases for their synthesis. Since the cost of the enzyme is an important factor for process economy, the use of whole-cell biocatalysts is attractive, since expensive purification and immobilization steps can be avoided. Display of the protein on the cell surface provides a possible way to reduce the mass transfer limitations of such biocatalysts. However, transaminases need to dimerize in order to become active, and furthermore, they require the cofactor pyridoxal phosphate; consequently, successful transaminase surface expression has not been reported thus far. In this work, we produced an Arthrobacter citreus omega-transaminase in Escherichia coli using a surface display vector based on the autotransporter adhesin involved in diffuse adherence (AIDA-I), which has previously been used for display of dimeric proteins. The correct localization of the transaminase in the E. coli outer membrane and its orientation toward the cell exterior were verified. Furthermore, transaminase activity was detected exclusively in the outer membrane protein fraction, showing that successful dimerization had occurred. The transaminase was found to be present in both full-length and proteolytically degraded forms. The removal of this proteolysis is considered to be the main obstacle to achieving sufficient whole-cell transaminase activity.
2.
Jalil, Kamran, et al.
(author)
Excellent antibacterial and anti-inflammatory efficacy of amoxicillin by AgNPs and their conjugates synthesized using Micromeria biflora crude flavonoid extracts
2024
In: Heliyon. - : Elsevier Ltd. - 2405-8440. ; 10:17
Journal article (peer-reviewed) abstract
Antibacterial resistance is considered to be one of the major causes for mortality in coming years. In recent years green nanotechnology played a key role in addressing this problem. Biocompatible metal nanoparticles have gained popularity owing to their excellent therapeutic effects and minimal side effects.Method: We report the synthesis of AgNPs and their amoxicillin conjugates (Ag-amoxi) using Micromeria biflora crude flavonoid extracts. The physicochemical properties of the synthesized NPs and Ag-amoxi conjugates were systematically evaluated using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR), and UV–visible (UV–Vis) spectroscopic techniques.Results: The average sizes of AgNPs and Ag-amoxi conjugates were 45 and 62 nm, respectively. We have also explored the antibacterial, antioxidant, anti-inflammatory, and analgesic properties of the AgNPs and Ag-amoxi conjugates through in vivo and in vitro analysis. The Ag-amoxi conjugates showed better antibacterial potential against Streptococcus Pneumoniae (S.P), Staphylococcus aureus (S.A), Pseudomonas aeruginosa (P.A), and Methicillin resistance Staphylococcus aureus (MRSA) strain both the drug and AgNPs. Similarly, in vivo anti-inflammatory studies revealed that both Ag-amoxi (68 %) and AgNPs (64 %) had strong anti-inflammatory effects, with (***p < 0.001) significance at a dose of 10 mg kg−1 body weight as compared to standard, amoxicillin (45 %), and flavonoids extract (48 %) at a dose of 100 mg kg−1. The findings of the antinociceptive activities (writhing and hot plate tests) demonstrated that the Ag-amoxi conjugates produced fewer writhing (15 in 20 s) and a shorter latency time of 22 s as compared to vehicle-treated (tramadol) animals, amoxicillin, and P.E at much lower doses. In vitro antioxidant studies revealed that the Ag-amoxi conjugate has the potential to be used as an antioxidant with an IC50 value of 43.58, compared with AgNPs (46.34), amoxicillin (58.17), compared to the standard of ascorbic acid (34.14).Conclusion: These results reveals that these biologically inspired AgNPs and Ag-amoxi conjugate could be used to improve antibiotic efficiency and could play a critical role in addressing the multidrug resistance problem in coming years.
3.
Näslund, Annika
(author)
Commentaries
2004
In: International Journal of Therapy and Rehabilitation. - : MA Healthcare Ltd. - 1741-1645 .- 1759-779X. ; 11:3, s. 126-
Journal article (other academic/artistic)
