How to Understand Zwitterion?
The term ‘Zwitterion’ is derived from the German word ‘zwitter’, which means ‘hybrid’ or ‘hermaphrodite’. A zwitterion is an ion that has both positive and negative electrical charges. Therefore, zwitterions are electrically neutral as the net formal charge is usually zero.
Zwitterion
A zwitterion is a molecule that includes both positive and negative regions of charge. The existence of amino acids as dipolar ions in a solid state is called zwitterions. To evaluate whether a substance is zwitterionic or not, the pH range must be specified. This is because the zwitterion changes to an anion in the presence of sufficient alkaline solution, and zwitterion changes to a cation in the presence of sufficient acid solution.
Characteristics of Zwitterion
The following are some of the characteristics of Zwitterion:
It can be formed by compounds that have both acid and base groups in their molecules such as ampholytes.
In this type of ion, the charged atoms are generally held together by one or more covalent bonds.
The atoms have stable, separated unit electrical charges in Zwitterrion Compounds.
These compounds contain quaternary ammonium cations.
Isoelectric Point
One of the main properties of a Zwitterion is that it has an isoelectric point, which is represented by pI, pH(I), IEP.
Generally, the pH has a great impact on the net charge on a molecule and its surrounding environment.
In this case, molecules become more charged either positively or negatively as a result of gain or loss in the number of protons.
In amino acids, the amino group is an effective proton acceptor and the carboxyl group is an effective proton donor.
The solubility of a molecule at a given pH is also impacted by the pI value.
Calculation of pH value
The pH value at the isoelectric point is calculated from the equilibrium constants such as acid and base of the Zwitterion. It is represented by the formula;
pI = (pKa1 + pKa2)/ 2
Where,
pI = isoelectric point,
Ka1 = the equilibrium constant of the acid.
Ka2 = the equilibrium constant of the base.
Applications of Zwitterion
Zwitterions are widely used in the process of separating protein molecules through the SDS PAGE (sodium dodecyl sulphate-polyacrylamide gel electrophoresis) method, which is one of the most popular techniques used in the field of molecular biology.
It has the potential to be used in a wide range of medical and biological-related fields.
Some of the most popular uses of zwitterions include medical implants, drug delivery, blood contact sensor, separation membrane, and antifouling coatings of biomedical implants (which help to prevent the build-up of microbial adhesion and biofilm formation).
To prevent subaquatic organisms from building up on boats and piers in the marine industry, Zwitterionic polymers are used.
Conclusion
Zwitterions are referred to as “inner salts” sometimes. Generally, dipolar compounds are not considered as zwitterions. It is due to the fact that the positive and negative signs on the amine oxide denote formal charges. Zwitterions are functional in the medicinal chemistry design considerations when working with acid, basic or neutral leads.
FAQs on Zwitterion
1. What is zwitterion and what are the characteristics of zwitterion?
A zwitterion is a molecule that includes both positive and negative regions of charge. The existence of amino acids as dipolar ions in a solid-state is termed as zwitterions. The following are some of the Characteristics of Zwitterion,
It can be formed by compounds that have both acid and base groups in their molecules such as ampholytes.
In this type of ion, the charged atoms are generally held together by one or more covalent bonds.
The atoms have stable, separated unit electrical charges in Zwitterrion Compounds.
These compounds contain quaternary ammonium cations.
2. What is the relationship between amino acid and Zwitterion?
Amino acids are one of the most common examples of zwitterions. It is made up of an ammonium or amino group and a carboxyl group. Where the amino group consists of a positive charge, and the carboxyl group contains a negative charge. Apart from amino acids, any compound that contains both acid and base centres can obtain a Zwitterion form.