Students can go through AP Inter 2nd Year Botany Notes 3rd Lesson Enzymes will help students in revising the entire concepts quickly.
AP Inter 2nd Year Botany Notes 3rd Lesson Enzymes
→ Almost all enzymes are proteins. There are some nucleic acids that behave like enzymes are called ribozymes Eg: 23 S rRNA.
→ Substrate ‘S’ has to bind the enzyme at its active site to form an ES complex. It dissociates into its products (P) and the unchanged enzyme.
→ Formation of ES complex has been explained with Lock and key hypothesis by Emil Fisher (1884) and later with Induced fit theory by Daniel E.Koshland (1973).
→ Each enzyme shows its highest activity at a particular temperature and pH called the optimum temperature and optimum pH.
→ When the binding of the chemical shuts off enzyme activity, this process is called inhibition and the chemical is called inhibitor.
→ When the inhibitor closely resembles substrate molecules and inhibits the activity of the enzyme is known as Competitive inhibitor.
→ If the inhibitor has no structural similarity with the substrate and forms an enzyme inhibitor complex at a point other than its active site is called Non-competitive enzyme inhibitor.
→ Enzymes are classified into six classes namely Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases and Ligases.
→ The enzyme code for Glucose – 6 – phosphotransferase is 2.7.1.2. The first digit denotes class, the second and third digits show sub class and sub-sub class whereas the fourth digit denotes serial number of the enzyme.
→ The protein part of the enzyme is called apoenzyme and the non-protein part is called cofactor.
→ Coenzymes are organic cofactors that is loosely bound to the apoenzyme.
→ Prosthetic groups are organic compounds that are tightly bound to the apoenzyme.
→ The essential chemical components of many coenzymes are vitamins.
Eg : Both NAD and NADP contain the vitamin Niacin.
→ Zinc is a cofactor for the proteolytic enzyme carboxy peptidase.
→ Enzymes are proteins which catalyse bio-chemical reactions in cells.
→ Almost all enzymes are proteins.
→ Some nucleic acids like ribozymes behave like enzymes.
→ Holo enzymes contain protein part called apoenzy me and non-protein part called co-factor. [IPE]
→ Co-faciors are three types (a) Prosthetic groups (b) Co-enzymes (c) Metal ions. [IPE]
→ An active site of an enzyme is a crevice into which the substrate fits.
→ Enzymes, through their active site, catalyse reactions at high rate
→ Enzymes get damaged at high temperatures (say above 40°C)
→ Enzymes isolated form organisms, living in sulphur springs retain their catalytic power even at 80°-90°C.
→ Thermal stability is an important quality of such enzymes.
→ The chemicals which stop the activities of the enzymes are called Enzyme inhibitors. [IPE]
→ They are 3 types (a) Competitive inhibitors (b)Non-competitive inhibitors (c) Feed back inhibitors.