Lyases catalyse the breakage of chemical bonds without undergoing hydrolysis or oxidation, leading to a new bond or ring structure.
Lyase belongs to the 4th class of the Enzyme group. They are divided into different subclasses depending on the substrate specificity.
- Decarboxylases
- Aldolases
- Fructose-6-phosphate phosphoketolase
- Isocitrate lyase
- Oxalomalate lyase
- Photolyase
- Dehydratses
- Hydratases
- Aconitase
- Chondroitin lyase
- Heparin lyase
- Carboxymethyloxysuccinate lyase
- Aspartate ammonia lyase
- Adenylosuccinate lyase
- Pyridoxal 5’ phosphate synthase
- Cysteine lyase
- Phosphoketolase
- Dehalogenases
- Guanylate cyclase
- Ferrochelatase
1. Decarboxylases
Also called carboxy-lyase, catalyze the addition or removal of carbon-carbon bonds in an organic compound. Some examples under decarboxylases are pyruvate decarboxylases, glutamate decarboxylases etc.
2. Aldolases
It is a common name for Fructose biphosphate aldolases. It breaks the carbon-carbon bond in fructose 1,6 biphosphate, leading to two carbonyl compounds. It is an essential enzyme in the glycolysis pathway.
3. Fructose-6-phosphate
It belongs to the aldehyde-lyase family of enzymes, where it breaks carbon-carbon bonds and forms an aldehyde containing byproduct.
4. Isocitrate Lyase
It is an enzyme in the glyoxylate pathway where it cleaves isocitrate to produce succinate and glyoxylate.
5. Oxalomalate Lyase
This is another carbon-carbon lyase enzyme. As the name suggests, its action substrate is oxalomalate and thus participates in decarboxylate metabolism
6. Photolyase
This is a unique type of lyase mainly because it requires light for its activity. It is involved in DNA repair mechanisms.
7. Dehydratase
They are a group of enzymes that assist information of double or triple carbon bonds by removing a water molecule. Some of the examples are Seriene dehydratase and Arogenate dehydratase.
8. Hydratases
This group of enzymes adds a hydroxyl group by using water molecules. They form an essential part of the fatty acid oxidation pathway.
9. Aconitases
It is involved in Kreb’s cycle where it isomerizes citrate into isocitrate.
10. Chondroitin Lyase
It is an inhibitory enzyme that inhibits the polymerization of its substrate, chondroitin sulphate. It is widely used in medical research.
11. Heparin Lyase
They are specific in their action, i.e. they only bring about the cleavage of 1-4 glycosidic linkage in heparin or heparin sulphate.
12. Carboxymethyloxysuccinate Lyase
It belongs to the group of lyase enzymes which cleave carbon-oxygen bonds. This enzyme produces two b-products, fumarates and glycolate.
13. Aspartate ammonia lyase
It is part of the lyase enzyme group involved in the cleavage of carbon-nitrogen bonds. It is essential for nitrogen metabolism as ammonia is one of its significant byproducts.
14. Adenylosuccinate lyase
It is involved in the purine biosynthesis pathway. It converts adenylosuccinate to AMP and fumarate.
15. Pyridoxal 5′ phosphate synthase
It catalyzes a multistep ring closure reaction that forms pyridoxine five phosphates. It is involved in the de-novo synthesis of Vitamin B6.
16. Cysteine Lyase
It is involved in cysteine and taurine metabolism. It uses pyridoxal phosphate as its cofactor.
17. Phosphketolase
This enzyme participates in three different pathways namely, the pentose phosphate pathway, methane metabolism as well as carbon fixation. It targets phosphate sugars in these pathways.
18. Dehalogenase
It is involved in cysteine and taurine metabolism. It uses pyridoxal phosphate as its cofactor.
19. Guanylate cyclase
This enzyme catalyzes the formation of cyclic Guanily monophosphate, an important secondary messenger in many cell signalling pathways.
20. Ferrochelatase
It is involved in the last step of the heme group. It catalyzes the reaction in the presence of ferric ions.
Summary
Our articles discuss different physiologically important lyase enzymes and some of the facts related to different lyase enzymes. Lyase enzymes are found in all organisms and thus make an important class of enzymes. Based on the bond they form and their target substrate, lyase enzymes are further divided into subclasses. Representative examples from those subclasses are discussed in this article.
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Hi…..I am Parul Jain, I have completed my Master’s in Biotechnology. I always like to explore new areas in the field of Biotechnology.
Apart from this, I like to read and travel.