Interplay of serum biomarkers bilirubin andγ-glutamyltranspeptidase in predicting cardiovascular complications in type-2 diabetes mellitus

This editorial synthesizes insights from a series of studies examining the interplay between metabolic and oxidative stress biomarkers in cardiovascular disease(CVD),focusing particularly on type-2 diabetes mellitus(T2DM)and acute coronary syndrome(ACS).The central piece of this synthesis is a study that investigates the balance between oxidative stress and antioxidant systems in the body through the analysis of serum bilirubin andγ-glutamyltranspeptidase(γ-GGT)levels in T2DM patients with ACS.This study highlights serum bilirubin as a protective antioxidant factor,while elevatedγ-GGT levels indicate increased oxidative stress and correlate with major adverse cardiovascular events.Complementary to this,other research contributions revealγ-GGT’s role as a risk factor in ACS,its association with cardiovascular mortality in broader populations,and its link to metabolic syndrome,further elucidating the metabolic dysregulation in CVDs.The collective findings from these studies underscore the critical roles ofγ-GGT and serum bilirubin in cardiovascular health,especially in the context of T2DM and ACS.By providing a balanced view of the body’s oxidative and antioxidative mechanisms,these insights suggest potential pathways for targeted interventions and improved prognostic assessments in patients with T2DM and ACS.This synthesis not only corroborates the pivotal role ofγ-GGT in cardiovascular pathology but also introduces the protective potential of antioxidants like bilirubin,illuminating the complex interplay between T2DM and heart disease.These studies collectively underscore the critical roles of serum bilirubin andγ-GGT as biomarkers in cardiovascular health,particularly in T2DM and ACS contexts,offering insights into the body’s oxidative and antioxidative mechanisms.This synthesis of research supports the potential of these biomarkers in guiding therapeutic strategies and improving prognostic assessments for patients with T2DM and some CVD.

Efficient Production of L-Theanine Using Immobilized Recombinant <i>Escherichia coli</i>Cells Expressing a Modified γ-Glutamyltranspeptidase Gene from <i>Pseudomonas nitroreducens</i>

L-Theanine (γ-glutamylethylamide) is a naturally occurring amino acid derivative known to have several beneficial physiological effects as a diet supplement, and to give an umami taste when used as a food additive. The compound is industrially produced by γ-glutamyltranspeptidase from Pseudomonas nitroreducens (PnGGT). Using recombinant PnGGT, we have shown previously that Trp385, Phe417, and Trp525 are key amino acid residues for recognition of acceptor substrates at the PnGGT active site. Here, we demonstrate that a recombinant W525D mutant of PnGGT produces L-theanine from ethylamine and L-glutamine more efficiently than wild-type PnGGT, attributable to an increased ratio of transfer activity to hydrolysis activity. An efficient production of L-theanine was achieved by immobilizing Escherichia coli cells expressing the W525D PnGGT mutant (E. coli-W525D) using 2% alginate as the supporting material. The highest L-theanine production using immobilized E. coli-W525D, representing a conversion rate of 90%, was achieved in optimal reaction conditions of pH 10, 40°C, and a substrate molar ratio of L-glutamine to ethylamine of 1:10. The immobilized E. coli-W525D retains 85% and 78% relative activity after storage for a month at 4°C and room temperature, respectively. Immobilized E. coli-W525D thus has strong potential for use in the future commercial production of L-theanine on a large scale.