What is the Difference Between Corrin Ring and Porphyrin Ring

Corrin ring and porphyrin ring are two macrocyclic compounds. Macrocyclic compounds are molecules featuring a ring structure of twelve or more atoms. These unique structures show different properties and applications, such as their ability to bind ions.

What is the difference between corrin ring and porphyrin ring? Corrin ring is non planar whereas porphyrin ring is somewhat planar.

Key Areas Covered

1. What is Corrin Ring  
      – Definition, Features, Structure
2. What is Porphyrin Ring
      – Definition, Features, Structure 
3. Similarities Between Corrin Ring and Porphyrin Ring
      – Outline of Common Features
4. Difference Between Corrin Ring and Porphyrin Ring
      – Comparison of Key Differences
5. FAQ: Corrin Ring and Porphyrin Ring
      – Answers to Frequently Asked Questions

Key Terms

Corrin Ring, Porphyrin Ring

What is Corrin Ring

Corrin ring is a complex organic molecule that resembles a porphyrin ring but lacks one carbon atom. This structure is found in the middle of vitamin B12, which gives it its characteristic properties and functions. The corrin ring is a macrocycle composed of four pyrrole-like subunits linked together. It typically coordinates a cobalt ion at the center.

Various chemical groups may attach to the corrin ring, influencing the specific form and function of vitamin B12. Though corrin does not exist independently on its own, it is the basic constituent of vitamin B12 and other related compounds called corrins. They are essential for various biological processes, such as DNA synthesis, the formation of red blood cells, and the functioning of nerves.

What is Porphyrin Ring

Porphyrin is a class of organic compounds that has a complex structure of four pyrrole rings linked together by methine bridges, creating a macrocyclic ring that gives its unique properties.

Heme is one of the widely known porphyrins, and it is the main component found in hemoglobin. Hemoglobin is responsible for carrying oxygen in the blood and is contained within heme. Thus, iron atoms inside the heme molecule bind to oxygen, which makes it easier to transport it through the human body.

Apart from hemoglobin, other important life processes depend on porphyrins. Another derivative of porphyrin is chlorophyll, which is responsible for photosynthesis in plants. It captures sunlight, converting its energy into chemical energy. In addition, they take part in cellular respiration aimed at generating power for cells. The structure of porphyrins allows them to absorb light strongly, giving them a particular coloration. This property makes them usable as dyes and also pigments.

Similarities Between Corrin Ring and Porphyrin Ring

1. Both are macrocyclic compounds.
2. Both consist of four pyrrole-like subunits connected to form a ring.
3. They have a conjugated system of alternating single and double bonds.
4. Both rings have a central cavity capable of coordinating metal ions.
5. They are essential components of some vital biomolecules.

Difference Between Corrin Ring and Porphyrin Ring

Definition

• Corrin ring is a macrocyclic structure composed of four linked pyrrole-like units, found in vitamin B12. Porphyrin ring, on the other hand, is a macrocyclic structure made up of four interconnected pyrrole units, found in hemoglobin and chlorophyll.

Structure

• Corrin has a 15-membered ring, while porphyrin has a 16-membered ring.

Conjugated System

• Porphyrin has a fully conjugated system, while corrin has a disrupted conjugated system.

Planar vs Non-Planar

• Porphyrin is a planar molecule, while corrin is non-planar.

Methine Bridge

• Porphyrin has a methine bridge (-CH-) between each pyrrole unit, but corrin lacks one of these methine bridges.

Binding

• Porphyrins commonly bind iron, while corrins typically bind cobalt.

Function

• Corrin rings are found in vitamin B12 with roles related to cobalt, whereas porphyrin rings are involved in oxygen transport (hemoglobin/myoglobin) and photosynthesis (chlorophyll).

Conclusion

Corrin ring and porphyrin are both macrocyclic compounds with different properties. Both structures are essential for life. Corrin rings are less planar and more constrained compared to the flat, aromatic porphyrin rings. This is the main difference between corrin ring and porphyrin ring.

FAQ: Corrin Ring and Porphyrin Ring

1. What is the difference between protoporphyrin and porphyrin rings?

Porphyrin is a general term for a molecule with four linked pyrrole rings. Protoporphyrin is a specific type of porphyrin with additional side chains, essential for forming heme, a component of hemoglobin.  

2. What is the difference between the heme group and the porphyrin ring?

A porphyrin ring is a cyclic molecule with four nitrogen atoms. A heme group is a porphyrin ring with an iron atom at its center. Heme is essential for oxygen transport in hemoglobin and other vital functions.

3. What is the function of the porphyrin ring?

The porphyrin ring is a molecule that binds with metals to form important compounds like heme (for oxygen transport) and chlorophyll (for photosynthesis). It’s essential for many biological processes. 

4. What is the function of the porphyrin ring in chlorophyll?

The porphyrin ring in chlorophyll functions as a light-absorbing antenna. It captures sunlight energy, which is then converted into chemical energy during photosynthesis.

5. What are the characteristics of the porphyrin ring?

Porphyrin rings are cyclic structures with four pyrrole subunits linked by methine bridges. They form complexes with metal ions.

Reference:

1. “Corrin – An Overview.” Science Direct.
2. “Porphyrin – An Overview.” Science Direct.

Image Courtesy:

1. “Corrin” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia
2. “Porphyrin” By Lukáš Mižoch – Own work (Public Domain) via Commons Wikimedia