describe how enzyme activity can be regulated through the us

describe how enzyme activity can be regulated through the use of isozymes. more specifically, how can the same enzymatic activity exhibit very different propertiesin different tissues via this mechanism?

Solution

Explanation:

Isozymes are enzymes that perform similar catalytic activities and are made up of different polypeptide chians.The combination of polypeptide chians and its subunits differ in different organs.Comparision of aminoacids sequence reveals that catalytic domain of the isoenzyme in different organs are highly conserved.The C terminal and N terminal of an isoenzyme play very great role in enzyme regulation.In enzyme regulation isoenzyme exhibit various modification in its N and in C terminus of its polypeptide chain in different organs .

Enzyme regulation through isoenzymes can be well explained by considering an example, isoenzymes of liver and heart varies by containing phosphorylation sites at its terminal peptide sequences.Phosphorylation of the N terminus of the liver enzyme results in inhibition of Fru-6-p,2-kinase,where as phosphorylation of C terminus in heart enzyme leads to the activation of Fru-6-p,2-kinase,by its interaction of phosphorylation at terminal peptide sequences at catalytic domain shows conformational changes on enzyme regulation.Like wise deletions in terminal peptide sequence of an isoenzyme also shows various changes in enzyme activity in dirrent organs.These isoenzymes exhibit diffrent kinetic properties like Km values (Km: the affinityof an enzyme towards its substrate).