Glucose Isomerase
Isomerase belongs to a particular class of enzymes that have the ability to catalyse reactions which involves a structural rearrangement of a molecule. For example, Alanine racemase is responsible for catalysing the conversion of L-alanine into its isomeric form, which is referred to as D-alanine. Mutarotase, which is also an isomerase, is responsible for catalysing the conversion of a-D- glucose into B-D-glucose. Ligase is one of the 50 enzymes that is involved in catalysing reactions that are involved in conversion.
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Triose Phosphate
Triose Phosphate Isomerase is considered to be an enzyme that is responsible for catalysing the reversible interconversion of the triose phosphate isomers dihydroxyacetone phosphate and D-glyceraldehyde 3-phosphate. Triose Phosphate Isomerase plays a key role in glycolysis and is required for producing efficient energy. When experts started searching for TPI, they were found in almost every organism, including animals such as mammals and insects, as well as in plants, fungi and bacteria. However, there were some bacteria like ureaplasmas who do not perform glycolysis that seem to lack TPI.
Glucose Isomerase
Glucose isomerase has the ability to catalyse the reversible isomerisation of glucose into fructose as well as xylose and xylulose. It is considered an essential enzyme that is basically used in the industrial production of high fructose corn syrup (HFCS). Despite the food industry, they are also helpful and play a major role in the production of biofuel.
Phosphohexose Isomerase
Phosphohexose Isomerase, which is alternatively known as glucose phosphate isomerase, is considered to be an enzyme that is present in the human body and is encoded by the GPI gene on chromosome 19. This gene is known for encoding a member of the glucose phosphate isomerase protein family. The protein which seems to get encoded was identified as a moonlighting protein which is based on its abilities to execute mechanistically distinct functions. Extracellularly, the encoded protein, which is also referred to as neuroleukin, has the ability to function as a neurotrophic factor that is responsible for promoting the survival of skeletal motor neurons and sensory neurons.
The encoded protein is also referred to as an autocrine motility factor which is based on the additional function as a tumour-secreted cytokine and angiogenic factor.
Peptidyl Prolyl Isomerase
Peptidyl Prolyl Isomerase is a type of enzyme that can be found in both prokaryotes and eukaryotes that are responsible for interconverting the cis and trans isomers of peptide bonds along with the amino acid proline. Proline is known to have an unusually conformationally restrained peptide bond which exists due to its cyclic structure with its side chain being bonded to secondary amine nitrogen. Most amino acids are considered for having a strong, energetic preference which helps in supporting the trans peptide bond conformation due to steric hindrance, but the unusual structure of proline is responsible for stabilising the cis form so that both isomers can get populated under conditions that are biologically relevant. Proteins that have prolyl isomerase activity includes cyclophilin, FKBPs and parvulin. According to different studies, it is proved that larger proteins also have chances of containing prolyl isomerase domains.
Proline is considered to be unique among all the natural amino acids as they have a relatively small difference in free energy between the cis configuration of their peptide bond and the transform, which is considered to be common.
Enoyl CoA Isomerase
Enoyl CoA isomerase is also considered as one type of enzyme that is responsible for catalysing the conversion of cis-or-trans double bonds of coenzyme A (CoA) bound fatty acids, which are present at gamma-carbon (position 3) into trans double bonds, which are present at beta-carbon (position 2). The enzyme plays a key role in the metabolism of unsaturated fatty acids in beta-oxidation.
It is clear from the above paragraph that Enoyl CoA isomerase is known to be involved in beta-oxidation, which is considered to be the most frequently used pathways in fatty acid degradation of unsaturated fatty acids along with double bonds, which are present at add-numbered carbon positions. They execute it by starting to shift the double bond's position in the acyl-CoA intermediates and trying to convert it to 3-cis or trans-enoyl-CoA to 2-trans-enoyl-CoA.
Conclusion
In this article, we discussed some important enzymes, among which some are found in the human body, and some are not, but a maximum of them are found in every living organism. These enzymes are part of nature and help to execute a lot of activities smoothly. They play a key role in different processes. This knowledge of various and distinct enzymes will help one in his/her career.
FAQs on Isomerase
1. What is the primary function of an isomerase enzyme?
The primary function of an isomerase enzyme is to catalyse the structural rearrangement of a substrate into one of its isomers. This means the enzyme changes the arrangement of atoms within a single molecule without altering its overall chemical formula. For instance, it can convert a cis-isomer to a trans-isomer or an L-amino acid to a D-amino acid.
2. What is an isomerase and can you provide a common example?
An isomerase is a major class of enzymes (EC 5) that facilitates the conversion of a molecule into one of its isomers. A well-known example is Triose Phosphate Isomerase, which plays a critical role in glycolysis. It catalyses the reversible conversion of dihydroxyacetone phosphate (DHAP) to D-glyceraldehyde 3-phosphate (G3P), ensuring both molecules can be used in the energy-producing pathway.
3. What is the importance of Glucose Isomerase in the food industry?
Glucose Isomerase is a commercially vital enzyme used to catalyse the conversion of glucose into fructose. Its primary application is in the industrial production of High-Fructose Corn Syrup (HFCS), a widely used sweetener in beverages and processed foods. This process is significant because fructose is sweeter than glucose, making HFCS an efficient and cost-effective sweetening agent.
4. Where are isomerase enzymes found in the human body?
Isomerase enzymes are found in nearly all cells throughout the human body, playing essential roles in various metabolic pathways. Key examples include:
- Phosphohexose Isomerase: Found in the cytoplasm of most cells, it participates in glycolysis.
- Peptidyl Prolyl Isomerase: Present in prokaryotes and eukaryotes, it is crucial for the correct folding of proteins.
- Triose Phosphate Isomerase: Essential for glycolysis and efficient energy production in cells.
5. How does Triose Phosphate Isomerase ensure efficiency in glycolysis?
Triose Phosphate Isomerase (TPI) is crucial for metabolic efficiency in glycolysis. During this pathway, a six-carbon sugar is split into two three-carbon molecules: dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (G3P). However, only G3P can proceed to the next energy-yielding steps. TPI rapidly converts the DHAP into G3P, effectively ensuring that the entire carbon content of the original glucose molecule is used for ATP production, thereby doubling the energy output.
6. What is the key difference between an isomerase and a transferase enzyme?
The key difference lies in the nature of the reaction they catalyse.
- An isomerase works on a single substrate, rearranging its internal atomic structure to form an isomeric product. The reaction involves only one molecule.
- A transferase, on the other hand, catalyses the transfer of a functional group (e.g., a phosphate or methyl group) from one molecule (the donor) to another (the acceptor). This reaction involves at least two substrates.
7. Why is the action of Peptidyl Prolyl Isomerase so important for protein function?
The amino acid proline has a unique cyclic structure that causes the peptide bond it forms to switch slowly between cis and trans configurations. This slow, uncatalysed isomerisation can be a major bottleneck in the process of protein folding. Peptidyl Prolyl Isomerase acts as a catalyst to speed up this conversion significantly. By doing so, it ensures that proteins can achieve their precise, functional three-dimensional shape in a biologically relevant timeframe, which is essential for their activity.
8. What are the main types of isomerases as per their classification?
Isomerases (EC 5) are sub-classified based on the specific type of isomerisation they perform. The main types include:
- Racemases and Epimerases: These enzymes invert the stereochemistry at a single chiral carbon atom in a substrate.
- Cis-trans-isomerases: They catalyse the rearrangement between cis and trans geometric isomers, often around a double bond.
- Intramolecular Oxidoreductases: These enzymes catalyse the oxidation of one part of a molecule while another part is reduced.
- Intramolecular Transferases (Mutases): They catalyse the transfer of a functional group from one position to another within the same molecule.
9. What role does Enoyl-CoA Isomerase play in fatty acid metabolism?
Enoyl-CoA Isomerase plays a key role in the beta-oxidation of unsaturated fatty acids. Standard beta-oxidation can only process fatty acids with trans double bonds at specific positions. When an unsaturated fatty acid has a double bond in a cis configuration or at the wrong position, Enoyl-CoA Isomerase repositions and reconfigures this double bond. This allows the beta-oxidation machinery to resume its process, enabling the cell to extract energy from a wider range of fats.
10. Can an isomerisation reaction happen without an enzyme?
Yes, isomerisation reactions can occur spontaneously without an enzyme, but the rate of such reactions is often extremely slow and not sufficient to support life processes. For example, the interconversion of glucose and fructose can happen on its own, but at a negligible rate. Enzymes like Glucose Isomerase increase the reaction rate by many orders of magnitude, making these crucial transformations possible on a timescale that is relevant for metabolism and industrial applications.
