Enzymes PDF

Enzymes: organic compounds (Proteins) that are produced by living cells to speed up & regulate the rate of rexn in & outside the cells & allow life to proceed at ordinary temp. Uses:- Medical treatment:- Enzyme streptokinase is used in dissolving blood clot. Genetic engineering:- Restriction endonu...

Enzymes: organic compounds (Proteins) that are produced by living cells to speed up & regulate the rate of rexn in & outside the cells & allow life to proceed at ordinary temp. Uses:- Medical treatment:- Enzyme streptokinase is used in dissolving blood clot. Genetic engineering:- Restriction endonuclease and ligases. Cleaning of hides:- Cleaning of meat and viscera with the aid of protease. Clearing of juices:- Pectinase is used for juice clarification. Alcoholic drinks:- Zymase is used in the preparation of fermented alcoholic beverage. Cheese formation:- Enzyme rennin from calf’s stomach used in making cheese. How enzyme works or speed up the reaction. Activation energy:- is the amount of energy necessary to initiate the chemical reaction. They work to lower down the activation energy thus speeds up the reaction to achieve early products. Nomenclature:- 1. These are named by adding suffix “ase” to the root word. Lipase, protease etc. 2. According to type of reaction catalysed. Dehydrogenase catalyse removal of hydrogen. 3. A new method consist of two part. First indicating substrate and second indicating the type of reaction catalysed. (DNA polymerase: synthesis of DNA) 4. Some named after their source. E.g. papain from papaya. 5. Some named as “IN” e.g. pepsin and trypsin as these are classified prior to modern nomenclature of classification. Example: Presence of enzyme make the process convenient can be sited through these examples. 1. The oxidation of fatty acid to carbon di oxide and water is not a gentle process in a test tube- extremes of high temperature, pH and corrosive chemicals are required. Yet in the body; such a reaction takes place smoothly and rapidly within a narrow range of pH and temperature. 2. In the laboratory, the average protein must be boiled for about 24 hours in a 20% HCl solution to achieve a complete breakdown. Yet in the body; the breakdown takes place in four hours or less under mild conditions of temperature and pH.  Mechanism: 1. Lock & Key 2. Induced Fit  Classification:- 1. Oxido-reductases:- that works to accept or donate the proton (H) or electron to shift substrate in the oxidized or reduced form. e.g. Dehydogenases. 2. Isomerases:- This class of enzyme catalyze various reactions that involves the formation of isomeric form of substrate on which they act. e.g. gluco-isomerases. 3. Hydrolases:- This classes of enzyme catalyzes various hydrolysis reaction, hydrolase generally involves addition or removal of water. e.g. esterases, carbohydrases etc. 4. Lyases:- This cleaves the bonds by means other than hydrolysis and oxidation. E.g. histidine decarboxylase splits C-C bond of histidine. 5. Ligases or synthetases: This catalyzes the joining of two substrate molecules by getting energy from ATP. e.g. Pyruvate carboxylase joins pyruvate and Co2. 6. Transferases:- This causes shifting of various functional group. e.g.Hexokinase transfer PO4- from ATP to Glucose. Prosthetic group:- certain non-protein part associated with enzymes is known as prosthetic group. they may be inorganic or organic in nature. Cofactor:- if prosthetic group is simple metal ions is known as cofactor. E.g. Fe2+. Cu2+, Mg2+. Coenzyme:- if prosthetic group is of organic nature, it is known as coenzyme. Apoenzyme:- if it works only in the presence of cofactor or coenzyme is known as apoenzyme. Holozyme:- A working combination of cofactor/coenzyme or apoenzyme is known as enzyme system or holozyme. Isozyme:- certain enzymes have slightly different molecular structure but similar catalytic function, are known as isoenzyme. E.g. Lactic dehydrogenase: changes pyruvate to lactate. Turnover number:- It is the number of molecules of substrate acted upon by an enzyme. Intracellular enzymes or endozymes:- most of the enzymes remain and function inside the cells. Respiratory enzymes are the examples. Extracellular enzymes or exozymes:- certain leaves the cell and function outside the cells. Salivary amylase etc. Zymogen or proenzyme:- certain enzyme produced in inactive form are known as zymogens. These are some of the examples where some coenzymes are needed to perform functionality of enzymes  Factors influences enzymatic activity:- 1. Enzyme concentration:- reaction rate increases with increase in enzyme concentration. 2. Substrate concentration:- reaction rate increases with increase in substrate concentration. Lessen in substrate concentration resulted in less frequent collisions with enzymes, thus reaction rate ceases. 3. Product concentration:- accumulation of product formation lowers enzymatic activity. 4. Temperature:- increase in temp causes effectiveness of product formation but upto a certain extent. Every 10 ˚C rise in temp doubles the reaction rate upto 45˚C. 5. pH:- there is an optimum pH to work upon. Based on alkaline, acidic & neutral pH suitability. 6. Poison:- some destroy tertiary structure of enzyme and make them ineffective. 7. Activator:- Pepsinogen are zymogen that become active only in presence of H+ ions. 8. Inhibitors:- competitive, non competitive and alloster. 9. Enzyme substrate complex:- greater the affinity of enzyme with substrate, more frequent is its catalytic function.  Inhibitors 1. Competitive inhibition 2. Non-competitve inhibition Digestion in human digestive system Enzyme related disorders: 1 Enzyme related disorders: 2 Enzyme related disorders: 3 Management of enzyme related metabolic disorders