The key difference between ribozymes and protein enzymes is that the ribozymes are RNA molecules that are capable of catalyzing certain specific biochemical reactions while the protein enzymes are protein molecules that are capable of catalyzing most of the biochemical reactions occurring in the living organisms.
Enzymes are biological catalysts, and they speed up the rate of biochemical reactions. Generally, all enzymes are proteins made up of amino acids. Hence they are also referred to as protein enzymes. However, there are specific RNA molecules that can act as catalysts of specific biochemical reactions. They are the ribozymes or ribonucleic acid enzymes. Therefore, both ribozymes and protein enzymes carry out the same function that is the catalyzing of biochemical reactions.
CONTENTS
1. Overview and Key Difference
2. What are Ribozymes
3. What are Protein Enzymes
4. Similarities Between Ribozymes and Protein Enzymes
5. Side by Side Comparison – Ribozymes vs Protein Enzymes in Tabular Form
6. Summary
What are Ribozymes?
Ribozymes are ribonucleic acid molecules that are capable of catalyzing specific biochemical reactions. Since they are RNA molecules, they refer to ribonucleic acid enzymes as well. These ribozymes are present in the ribosomes. The main reactions that ribozymes catalyze are cleavage and ligation of RNA and DNA and peptide bond formation.
Figure 01: Ribozyme Action
Furthermore, ribozymes act as a part of the large subunit of ribosomes and participate in the activities of protein synthesis such as RNA splicing, tRNA synthesis, etc. Hammerhead ribozyme, the Varkud satellite (VS) ribozyme, Leadzyme and the hairpin ribozyme are few examples of ribozymes.
What are Protein Enzymes?
Protein enzymes are biological catalysts that accelerate most of the biochemical reactions occurring in plants, animals, microorganisms and other living organisms. Generally, in the absence of enzymes, most of the biochemical reactions show a very slow rate. Hence, enzymes are essential biomolecules in all living organisms. Structurally, enzymes are made up of amino acid sequences. Hence, they are specific proteins.
Function
Enzymes accelerate reactions by binding with the substrate through their catalytic sites. In addition, enzymes are specific for their substrates. More often, the shape of the catalytic site is complementary to the shape of the substrates. Hence, a particular type of enzymes can regulate specific types of reactions. Hence, there are many types of enzymes in living cells. Amylase, maltase, trypsin, protease, pepsin, lipase, polymerase, cellulase, alcohol dehydrogenase, sucrase and lactase are some examples for enzymes.
Figure 02: Enzymes
Each enzyme works best at its optimal temperature and pH. Hence, we should provide optimal conditions during the reactions. If the temperature exceeds the denaturing temperature of the proteins, shapes of the enzymes may change and their activities may shut down. In the end, the rate of the reaction becomes slow. If the enzyme works at normal conditions, it remains unchanged even after the reaction. Hence, it can participate in another reaction. Some enzymes require cofactors for the functioning. Cofactors are inorganic or organic molecules. They help enzymes by binding with the enzyme loosely or tightly.
What are the Similarities Between Ribozymes and Protein Enzymes?
- Both ribozymes and protein enzymes are biological catalysts.
- They are capable of catalyzing biochemical reactions that occur in living organisms.
- Also, both are macromolecules.
- Besides, they have diverse structures and mechanisms.
What is the Difference Between Ribozymes and Protein Enzymes?
The key difference between ribozymes and protein enzymes is that ribozymes are RNA molecules while protein enzymes are globular proteins. Therefore, ribozymes are polymers of ribonucleotides while protein enzymes are polymers of amino acids. Thus, this is also a difference between ribozymes and protein enzymes.
Moreover, a further difference between ribozymes and protein enzymes is that the ribozymes are present in the ribosomes while protein enzymes are present everywhere in the cell even within the many cell organelles.
The below infographic shows more details on the difference between ribozymes and protein enzymes.
Summary – Ribozymes vs Protein Enzymes
Ribozymes and protein enzymes are two types of biological catalysts present in living cells. They perform a similar action. However, ribozymes are RNA molecules composed of ribonucleotides while protein enzymes are globular proteins composed of amino acids. Furthermore, ribozymes are present in the ribosomes while protein enzymes are present everywhere in the cell. Moreover, ribozymes are less abundant while protein enzymes are more abundant in the cell. Therefore, this is the summary of the difference between ribozymes and protein enzymes.
Reference:
1. Walter, N G, and D R Engelke. “Ribozymes: Catalytic RNAs That Cut Things, Make Things, and Do Odd and Useful Jobs.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, Oct. 2002. Available here
2. Cooper, Geoffrey M. “The Central Role of Enzymes as Biological Catalysts.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, 1 Jan. 1970. Available here
Image Courtesy:
1.”Ribozyme”By Robinson R (CC BY 2.5) via Commons Wikimedia
2.”Glucosidase enzyme”By Thomas Shafee – Own work, (CC BY-SA 4.0) via Commons Wikimedia
Why do cells use protein enzyme and not Ribozyme in catalyzing every biochemical processes?