What is the Difference Between Luciferase and GFP

The key difference between luciferase and GFP is that luciferase is an enzyme that produces light when it oxidises its substrate luciferin, while GFP (green fluorescent protein) is a protein that displays bright green fluorescence when exposed to light in the blue to ultraviolet range.

Bioluminescence is due to light produced by a chemical reaction within a living organism. It is a type of chemiluminescence. Therefore, bioluminescence can be defined as chemiluminescence that takes place inside a living organism. Most bioluminescent organisms are found in the ocean. These organisms include fish, bacteria, and jellies. Some bioluminescent organisms such as fireflies and fungi are found in the land. Bioluminescent organisms are not native to freshwater. Normally, bioluminescent organisms contain molecules like luciferase and GFP for this purpose. Luciferase and GFP are two proteins that are capable of producing bioluminescence.

CONTENTS

1. Overview and Key Difference
2. What is Luciferase 
3. What is GFP
4. Similarities – Luciferase and GFP
5. Luciferase vs GFP in Tabular Form
6. Summary – Luciferase vs GFP

What is Luciferase?

Luciferase is an enzyme that produces light when it oxidises the substrate luciferin. This enzyme catalyses chemical reactions in living organisms that result in the emission of photons. It is usually distinguished from a photoprotein. The name “luciferase” was first used by Raphael Dubois, who invented the words luciferin and luciferase. Various organisms regulate their light production using different luciferases in a variety of light-emitting reactions. The majority of studied luciferases have been found in animals, including fireflies, marine organisms like copepods, jellyfish and sea pansy. Luciferases also have been found in luminous fungi, luminous bacteria and dinoflagellates.

Luciferin is the substrate for the luciferase enzyme. Luciferase is classified as oxidoreductases. It means it acts on single donors with the incorporation of molecular oxygen. The chemical reaction catalysed by firefly luciferase takes place in two steps, as mentioned below.

Luciferin + ATP → Luciferyl adenylate + PPi

Luciferyl adenylate + O₂→ Oxyluceferin + AMP + Light

This enzyme is widely used in biotechnology, for microscopy, and as a reporter gene. However, unlike fluorescent proteins, luciferase does not require an external light source. But it requires the addition of its substrate consumable luciferin.

What is GFP?

GFP (green fluorescent protein) is a protein that displays a bright green fluorescence when exposed to light in the blue to ultraviolet range. The label GFP normally refers to the protein first isolated from the jellyfish Aequorea victoria, and it is sometimes called avGFP. However, GFPs have been found in other organisms, including corals, sea anemones, copepods, zoanthids and lancelets.

GFP is an excellent tool that can be used in many forms of Biology. This is due to its ability to form an internal chromophore without requiring any accessory cofactors, gene products, enzymes, or substrates other than molecular oxygen. In cell and molecular biology, the GFP gene is commonly used as a reporter of expression. It has also been used in modified forms to make biosensors. Furthermore, Roger Y. Tsien, Osamu Shimomura, and Martin Chalfie were awarded the Nobel Prize in 2008 for their discovery and development of the green fluorescent protein.

What are the Similarities Between Luciferase and GFP?

• Luciferase and GFP are two proteins that are capable of producing bioluminescence.
• They are made up of amino acids.
• Both need molecular oxygen in the bioluminescence
• Both can be used as reporter molecules in biological research.
• They are both found in animals.

What is the Difference Between Luciferase and GFP?

Luciferase is an enzyme that produces light when it oxidises its substrate luciferin, while GFP is a protein that displays bright green fluorescence when it is exposed to light in the blue to ultraviolet range. So, this is the key difference between luciferase and GFP. Furthermore, luciferase does not need an external light source to exhibit bioluminescence, while GFP needs an external light source to exhibit bioluminescence.

The following infographic lists the differences between luciferase and GFP in tabular form for side by side comparison.

Summary – Luciferase vs GFP

Bioluminescence is due to light produced by a chemical reaction within a living organism. Luciferase and GFP are two proteins that are capable of producing bioluminescence. Luciferase is an enzyme that produces light via oxidising its substrate luciferin, while GFP is a protein that displays bright green fluorescence when exposed to light in the blue to ultraviolet range. Thus, this summarises the difference between luciferase and GFP.

Reference:

1. “Luciferase.” An Overview | ScienceDirect Topics.
2. Remington, S James. “Green Fluorescent Protein: A Perspective.” Protein Science : a Publication of the Protein Society, Wiley Subscription Services, Inc., A Wiley Company, Sept. 2011.

Image Courtesy:

1. “Luciferase” By Oregon State University (CC BY-SA 2.0) via Flickr
2. “GFP (Green Fluorescent Protein) model (4322934668)” By Umberto Salvagnin from Italy – GFP (Green Fluorescent Protein) model (CC BY 2.0) via Commons Wikimedia