Zwitterion
Zwitterion — A molecule carrying both positive and negative charges simultaneously but with a net charge of zero. Amino acids exist as zwitterions at their isoelectric point.
What Is a Zwitterion?
A zwitterion is a molecule that simultaneously carries both a positive and a negative charge. All free amino acids exist as zwitterions at physiological pH: the amino group is protonated (NH3+) and the carboxyl group is deprotonated (COO-), giving a net charge of zero despite bearing two formal charges. Peptides can also be zwitterionic when their overall net charge is zero.
Relevance to Peptide Chemistry
- Solubility: Zwitterionic amino acids are highly water-soluble despite being neutral overall
- pI: Peptides at their pI are predominantly zwitterionic with minimum net charge
- Chromatography: The zwitterionic nature affects retention in IEX and HILIC modes
Frequently Asked Questions
What is Zwitterion?
A molecule carrying both positive and negative charges simultaneously but with a net charge of zero. Amino acids exist as zwitterions at their isoelectric point.
Why is Zwitterion important in peptide research?
Zwitterion is a fundamental concept in chemistry as it relates to peptide science. It directly influences experimental design, compound characterization, and the reliability of research outcomes across biochemistry and molecular biology disciplines.