3 research outputs found
Cofactor Tail Length Modulates Catalysis of Bacterial F420-Dependent Oxidoreductases
F420 is a microbial cofactor that mediates a wide range of physiologically important
and industrially relevant redox reactions, including in methanogenesis and tetracycline
biosynthesis. This deazaflavin comprises a redox-active isoalloxazine headgroup
conjugated to a lactyloligoglutamyl tail. Here we studied the catalytic significance of
the oligoglutamate chain, which differs in length between bacteria and archaea. We
purified short-chain F420 (two glutamates) from a methanogen isolate and long-chain
F420 (five to eight glutamates) from a recombinant mycobacterium, confirming their
different chain lengths by HPLC and LC/MS analysis. F420 purified from both sources
was catalytically compatible with purified enzymes from the three major bacterial families
of F420-dependent oxidoreductases. However, long-chain F420 bound to these enzymes
with a six- to ten-fold higher affinity than short-chain F420. The cofactor side chain also
significantly modulated the kinetics of the enzymes, with long-chain F420 increasing the
substrate affinity (lower Km) but reducing the turnover rate (lower kcat) of the enzymes.
Molecular dynamics simulations and comparative structural analysis suggest that the
oligoglutamate chain of F420 makes dynamic electrostatic interactions with conserved
surface residues of the oxidoreductases while the headgroup binds the catalytic site. In
conjunction with the kinetic data, this suggests that electrostatic interactions made by
the oligoglutamate tail result in higher-affinity, lower-turnover catalysis. Physiologically,
we propose that bacteria have selected for long-chain F420 to better control cellular
redox reactions despite tradeoffs in catalytic rate. Conversely, this suggests that
industrial use of shorter-length F420 will greatly increase the rates of bioremediation and
biocatalysis processes relying on purified F420-dependent oxidoreductases
The Role of Teacher Stance When Infusing Inquiry Questioning Into Middle School Science Classrooms
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Educating integrated catalysts: transforming business schools toward ethics and sustainability
Joining the sharpening critique of conventional University-based business school education, we argue that educating integrated catalysts is necessary to meet current sustainability challenges. The key feature of moving toward the integration required at the individual level is focusing on developing students' capacity for moral and cognitive maturity. Practically, this makes the practice of genuine dialogue focal as core interpersonal method for educating management students. In supporting such education, business schools must however first transform themselves. Acting as transformative social enterprises, they can demonstrate being a part in critically questioning and improving the impact and relevance of management on the flourishing of wider society and the practice of an ethically oriented economy. We offer practical suggestions and implications for future business education reform