A transmembrane anion transporter selective for nitrate over chloride
Paul V Santacroce1, Oluyomi A Okunola, Peter Y Zavalij
1Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
Chemical Communications (Cambridge, England)
|October 10, 2006
Summary
A novel C3-symmetric triamide acts as a selective nitrate (NO3-) anion transporter across lipid vesicles. This proton-nitrate (H+-NO3-) co-transporter influences liposome pH during nitrate/chloride (NO3-/Cl-) gradients.
Area of Science:
- Supramolecular chemistry
- Anion transport
- Membrane biophysics
Background:
- Anion transport across biological membranes is crucial for cellular functions.
- Selective anion transporters are valuable tools in chemical biology and medicine.
- Nitrate (NO3-) transport is implicated in various physiological and environmental processes.
Purpose of the Study:
- To develop a synthetic molecule capable of selective nitrate anion transport.
- To investigate the mechanism of proton-nitrate (H+-NO3-) co-transport.
- To study the effect of nitrate transport on the internal pH of lipid vesicles.
Main Methods:
- Synthesis and characterization of a C3-symmetric triamide.
- Liposome-based transport assays to measure NO3- flux.
- Monitoring of internal pH changes using pH-sensitive fluorescent probes.
- Investigation of anion selectivity using different halide and oxyanion gradients.
Main Results:
- The C3-symmetric triamide demonstrated selective transport of NO3- anions over other anions like Cl-.
- The molecule functions as a H+-NO3- co-transporter, coupling proton influx to nitrate transport.
- Significant alterations in liposome internal pH were observed in the presence of a NO3-/Cl- gradient, confirming the co-transport mechanism.
Conclusions:
- C3-symmetric triamide is an effective synthetic transporter for NO3- anions.
- The H+-NO3- co-transport mechanism provides a means to modulate pH gradients across membranes.
- This study offers a novel synthetic tool for studying anion transport and membrane potential.
Related Concept Videos
01:44The Significance of Membrane Transport
The transport of solutes across the cell membrane is essential for metabolic processes, like maintaining cell size and volume, generating the action potential, exchanging nutrients and gases, etc. Membrane transport can be either passive or active. It can be simple diffusion, facilitated, or mediated transport aided by transport proteins such as transporters and channels.
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
01:14Active Transport
Active transport is a critical biological process that allows cells to move solutes against an electrochemical gradient. This process requires direct energy input and is characterized by its selectivity, saturability, and susceptibility to competitive inhibition.
Primary active transporters, like Na+, K+ and -ATPase, directly utilize ATP to move ions across the membrane. These transporters play significant roles in various physiological processes. For instance, Na+, K+ and -ATPase maintain...
Primary active transporters, like Na+, K+ and -ATPase, directly utilize ATP to move ions across the membrane. These transporters play significant roles in various physiological processes. For instance, Na+, K+ and -ATPase maintain...
01:32Secondary Active Transport
One example of how cells use the energy contained in electrochemical gradients is demonstrated by glucose transport into cells. The ion vital to this process is sodium (Na+), which is typically present in higher concentrations extracellularly than in the cytosol. Such a concentration difference is due, in part, to the action of an enzyme "pump" embedded in the cellular membrane that actively expels Na+ from a cell. Importantly, as this pump contributes to the high concentration of...
01:55Secondary Active Transport
One example of how cells use the energy contained in electrochemical gradients is demonstrated by glucose transport into cells. The ion vital to this process is sodium (Na+), which is typically present in higher concentrations extracellularly than in the cytosol. Such a concentration difference is due, in part, to the action of an enzyme “pump” embedded in the cellular membrane that actively expels Na+ from a cell. Importantly, as this pump contributes to the high concentration of...
01:32Secondary Active Transport
One example of how cells use the energy contained in electrochemical gradients is demonstrated by glucose transport into cells. The ion vital to this process is sodium (Na+), which is typically present in higher concentrations extracellularly than in the cytosol. Such a concentration difference is due, in part, to the action of an enzyme "pump" embedded in the cellular membrane that actively expels Na+ from a cell. Importantly, as this pump contributes to the high concentration of...
01:29Primary Active Transport
In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or electrochemical gradient. There are two types of active transport: primary active transport and secondary active transport. Primary active transport utilizes chemical energy from ATP to drive protein pumps embedded in the cell membrane. With energy from ATP, the pumps transport ions against their electrochemical gradients—a direction they would not...