University:
Liberty University
Course:
BIOM 500 | Introduction to Biomedical Sciences
Academic year:

2024
Views:

391

Pages:

5
Author:

Sheha A.

**Enzymes** These are defined as biocatalysts synthesized by the living tissue, protein in nature, thermolabile, and colloid in character. Specific in action, which increase the rate of reaction without getting consumed in the process. All enzymes are proteins. Enzymes with 2 or more subunits are called oligomeric enzymes. Some enzymes required the presence of certain additional organic or inorganic substance. Enzymes conjugated with non-protein part are called holoenzymes. The protein part of the holoenzyme is called apoenzyme. Non-protein part of the conjugate protein called prosthetic groups. **Isoenzymes** Different form of the same enzyme catalyzing the same reaction are called isoenzymes or isozymes. These are slight variation in the gene sequence and amino acid sequence. Hence these enzymes have different Km values or Vmax. * Not all enzymes have isoenzyme forms. Only polymeric enzymes exhibit the isoenzyme forms. * Different isoenzymes have the difference in their heat stability, tissue localization, and specificity to inhibitors. Hence they are useful in diagnosis of particular disease. **Glucokinase** * Isomeric form of glucokinase that is hexokinase * Hexokinase and glucokinase are two enzymes which are having the different localization * Hexokinase present in all body cells and glucokinase present in liver and pancreas cells * They are also having different Km values and Vmax values. Km value is higher for glucokinase and Km value lower for hexokinase * That means: * Hexokinase is active at low glucose concentration whereas glucokinase is active at high glucose concentration **2. Lactate dehydrogenase has the 5 isoenzymes** LDH-1, LDH-2, LDH-3, LDH-4, LDH-5 **3. Creatine kinase / Creatine phosphokinase** has CK-MM (CPK-1), CK-MB (CPK-2), CK-BB * LDH-1 and CK-MB is very important to diagnosis of myocardial infarction **4. Isoenzymes of lactate dehydrogenase and creatine phosphokinase**