Question

Which of the following is an example of isozyme?
A. α-amylase
B. Glucokinase
C. Lactate dehydrogenases
D. All of the above

Answer 1

There are some special types of protein found in the human body that act as biological catalysts. These types of proteins are known as enzymes. The enzymes accelerate different types of biological and chemical reactions and the enzymes act upon which molecules are known as substrates.

Complete answer:
The enzymes are a special type of protein which function as biological catalysts to accelerate different types of biological and chemical reactions. When the enzymes catalyse the same chemical reaction then the enzymes are known as isozymes.
Isozymes are a form of the enzyme which are also known as isoenzymes. Isozyme differs in amino acid sequence but they catalyse the same chemical reaction. Generally, these types of enzymes show different kinetic parameters or different regulatory properties. The presence of isozymes helps in the process of metabolism which is required for the purpose of meeting the particular needs of a biological function. In the field of biochemistry, isozymes or isoenzymes are isoforms of enzymes. In several cases, they are coded for by homologous genes that have been dismissed over time. Isozymes refer to those enzymes from different genes that process or catalyse the same reaction.
Isozymes can be described as different variants of the same enzyme which have identical functions and these are found in the same individual. Generally, the isozymes are the result of gene duplication. Though it can be also produced from polyploidization or hybridization. The function of the new variant remains identical to the original, then it is likely that one or the other will be lost due to accumulation of mutations. It results in a pseudogene.
Glucokinase is an example of an isozyme which is a variant of hexokinase and it is not inhibited by glucose 6-phosphate. α-amylase which is present in wheat endosperm possesses 16 isozymes. The enzyme lactate dehydrogenase is a tetramer made of two different subunits which have 5 isozymes.

Hence, the correct answer is option (D).

Note: Isozymes are such types of enzymes which catalyse the same chemical reaction. Though their amino acid sequence is different. Isozymes increase the tuning of metabolism for the purpose of meeting particular needs. It was described by R. L. Hunter and Clement Markert in the year 1957. α-amylase, glucokinase, lactate dehydrogenases all are the example of isozymes.