Effective metabolic
pathways are essential for the construction
of in vitro systems mimicking the biochemical complexity of living
cells. Such pathways require the inclusion of a metabolic branch that
ensures the availability of reducing equivalents. Here, we built a
minimal enzymatic pathway confinable in the lumen of liposomes, in
which the redox status of the nicotinamide cofactors NADH and NADPH
is controlled by an externally provided formate. Formic acid permeates
the membrane where a luminal formate dehydrogenase uses NAD
+
to form NADH and carbon dioxide. Carbon dioxide diffuses out of
the liposomes, leaving only the reducing equivalents in the lumen.
A soluble transhydrogenase subsequently utilizes NADH for reduction
of NADP
+
thereby making NAD
+
available again
for the first reaction. The pathway is functional in liposomes ranging
from a few hundred nanometers in diameter (large unilamellar vesicles)
up to several tens of micrometers (giant unilamellar vesicles) and
remains active over a period of 7 days. We demonstrate that the downstream
biochemical process of reduction of glutathione disulfide can be driven
by the transfer of reducing equivalents from formate via NAD(P)H,
thereby providing a versatile set of electron donors for reductive
metabolism.
The interactions between biomembranes and particles are key to many applications, but the lack of controllable model systems to study them limits the progress in their research. Here, we describe...
Polymer‐based nanoparticles have an increasing presence in research due to their attractive properties, such as flexible surface functionality design and the ability to scale up production. Poly(ionic liquid) (PIL) nanoparticles of size below 50 nm are very unique in terms of their high charge density and internal onion‐like morphology. The interaction between PIL nanoparticles and giant unilamellar vesicles (GUVs) of various surface charge densities is investigated. GUVs represent a convenient model system as they mimic the size and curvature of plasma membranes, while simultaneously offering direct visualization of the membrane response under the microscope. Incubating PIL nanoparticles with GUVs results in poration of the lipid membrane in a concentration‐ and charge‐dependent manner. A critical poration concentration of PILs is located and the interactions are found to be analogous to those of antimicrobial peptides. Microbial mimetic membranes are already affected at submicromolar PIL concentrations where contrast loss is observed due to sugar exchange across the membrane, while at high concentrations the collapse of vesicles is observed. Finally, a confocal microscopy–based approach assessing the particle permeation through the membrane is reported and a mechanism based on bilayer frustration and pore stabilization via particle integration in the membrane is proposed.
Recently, we demonstrated the use of 31 P CODEX (Centerband-Only Detection of Exchange) NMR to measure lateral diffusion of phospholipids.Here we demonstrate the multiplexing capabilities of CODEX, i.e. simultaneous measurement of multiple phospholipid lateral diffusion coefficients, and compare the effects of polylysine and a model anti-microbial peptide, KL-14 (KKLLK KAKKL LKKL), on lateral diffusion of various anionic phospholipids.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.