- Information
- AI Chat
Properties of Isozymes
Biochemistry and molecular biology (Bmb368)
Pondicherry University
Preview text
Molecular Biology
Properties of Isozymes
Isozymes are different variants of the same enzyme that have identical functions and are found in the same person. This definition includes enzyme variants produced by different genes and thus representing different loci (referred to as isozymes) as well as enzymes produced by different alleles of the same gene (described as allozymes).
Isozyme is a special type of enzyme, which is formed due to structural changes in a gene. The isozymes are not only the difference between individuals’ genes, but can also exist at the level of individual cells. They are usually formed under the influence of external factors and reflect the state of the organism.
Isozymes are most commonly the result of gene duplication, but they can also be the result of polyploidization or nucleic acid hybridization. If the function of the new variant remains the same as the original, it is likely that one or both will be lost as
mutations accumulate, resulting in a pseudogene. However, if the mutations do not immediately stop the enzyme from working.
The main function of isozymes is the differentiation between individuals of a species based on their genetic differences. Isozymes are defined as enzymes that have the same chemical structure, but differ in terms of charge and kinetic rate constants. All organisms produce some enzymes; however, some may lack certain specific isozymes, while others may have duplicate sets of these enzymes. This is how the different species become differentiated. There is not only one type of enzyme system, but rather thousands of them, each with its own unique role. These characteristics determine the metabolic pathways of the organism.
Allozymes can be caused by point mutations or insertion-deletion (indel) events in the gene's DNA coding sequence. A new allozyme can undergo three changes, just like any other new mutation: The new allele is most likely non-functional, in which case it will have low fitness. Alternatively, if the changed amino acid residue is in a relatively unimportant part of the enzyme, such as a long distance from the active site, the mutation may be selectively neutral and subject to genetic drift. In rare cases, the mutation may result in a more efficient enzyme or one that can catalyze.
✓ Applications of Isozymes
In general, isozymes can be used to satisfy the metabolic needs of various tissues and developmental stages. Lactate dehydrogenase is an example of an enzyme with multiple isozymes (LDH). This enzyme catalyzes the synthesis of glucose in anaerobic glucose metabolism. This enzyme's isozymes are classified into two types: H isozyme and M isozyme. The H isozyme is more prevalent in the heart, whereas the M isozyme is more prevalent in skeletal muscle. Both isozymes have two polypeptide chains, and 75% of the amino acid sequence for the chains is shared by both. Both isozymes metabolize glucose, but the H isozymes have a greater affinity for their substrates than the M isozyme.
Properties of Isozymes
Course: Biochemistry and molecular biology (Bmb368)
University: Pondicherry University
This is a preview
Access to all documents
Get Unlimited Downloads
Improve your grades
