Improvement of production yield of l-cysteine through in vitro metabolic pathway with thermophilic enzymes

In Situ and Ex Situ Raman Studies of Cysteine’s Behavior on a Titanium Surface in Buffer Solution

In this paper, surface-enhanced Raman spectroscopy (SERS) was used to investigate the adsorption process of cysteine (Cys). Studies were carried out in the presence of phosphate-buffered saline solution (PBS), at pH 7.4, and acidified to pH 5, 3, and 1, on the surface of Ti for implant application. In situ SERS spectra obtained for the Cys/Ti solution system, after 24 h of immersion time, indicated that the buffer solution strongly influences the adsorption behavior of Cys on the Ti surface. This results in a decrease in Cys adsorption on the Ti surface, in the range of pH 7.4 to 3. The strong interaction between a sulfur atom of Cys and a Ti surface was observed only at pH = 1, under strongly acidic conditions. In contrast, ex situ SERS spectra recorded for the same samples but in a dried Cys/Ti system show a completely different behavior of Cys on the Ti surface. Formation of a disulfide (S-S) bond has occurred as a result of the dimerization or aggregation of Cys molecules on the Ti surface. Detailed analysis of the adsorption behavior of Cys on the Ti surface can be very important in the preparation of bioactive materials (i.e., coated by organic layers).

One-step preparation of cell-free ATP regeneration module based on non-oxidative glycolysis using thermophilic enzymes

Adenosine triphosphate (ATP) is an essential cofactor for energy-dependent enzymatic reactions that occur during in vitro biochemical conversion. Recently, an enzyme cascade based on non-oxidative glycolysis, which uses starch and orthophosphate as energy and phosphate sources, respectively, for the regeneration of ATP from adenosine diphosphate, has been developed (Wei et. al., ChemCatChem 2018 , 10 , 5597-5601). However, the 12 enzymes required for this system hampered its practical usability and further testing potential. Here, we addressed this issue by constructing co-expression vectors for the simultaneous gene expression of the 12 enzymes in a single expression strain. All enzymes were sourced from (hyper)thermophiles, which enabled a one-step purification via a heat-treatment process. We showed that the combination of the two enabled the ATP regeneration system to function in a single recombinant Escherichia coli strain. Additionally, this work provides a strategy to rationally design and control proteins expression levels in the co-expression vectors.