enzyme ppt

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gives a brief description about enzymes & all the aspects related to it including enzyme inhibition & immobilization of enzymes.

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ENZYMATIC REACTIONS BY :- AKSHARA BABITA HIMANSHI & NAVREET

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WHAT ARE ENZYMES ? Enzymes are soluble, colloidal molecules which are produced by living cells. All these enzymes are globular proteins with a complex 3-D structures, capable of binding substrate molecules . Act as biological catalyst and accelerates a reaction . Required for every chemical reaction taking place in body . Found in all living organisms.

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PROPERTIES OF ENZYMES ◊ COLLOIDAL NATURE :- Form colloidal system with water due to its large size. ◊ CATALYTIC NATURE :- Accelerate the rate of reaction. The catalytic power of an enzyme is measured by the turnover number. ◊ SPECIFICITY :- Enzymes are highly specific in their action. They may show absolute specificity, group specificity, optical specificity or geometrical specificity. ◊ THERMOLABILITY :-

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◊ ph SENSITIVITY :- ◊ REVERSIBILITY OF REACTION :- Enzymes are capable of bringing about reversion in a chemical reaction. ◊ ACTIVE SITE :- It is the functional domain of the enzyme which actually binds with the substrate.

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COMPONENTS OF AN ENZYME Some enzymes are made up of entirely proteins but most of the enzymes are Holoenzymes. HOLOENZYME APOENZYME COFACTOR/COENZYME - Protein component - Non-protein component - Act as electron carriers - Present in inactive form - Activated by cofactor - If the cofactor is org. mol. It is called coenzyme - Cofactor :- Mg+2 , Zn+2 . Coenzymes :- NAD+ , NADP+

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MECHANISM OF ENZYME ACTION Enzymes work by lowering the activation energy (min. energy required for a chm. rxn to take place) The surface of the substrate contacts a specific region of enzyme called active site . A temporary intermediate compound forms called enzyme- substate complex . The substrate molecule is transformed by the rearrangement of existing atoms, or in combination with another substrate moleule . The transformed substrate molecule / the product of the rxn are released from the enzyme molecule coz they no longer fit in the active site. The enzyme is now free to react with other substrate molecules. E + S ES EP E + P

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2 MODELS LOCK KEY MODEL INDUCED FIT MODEL

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FACTORS AFFECTING ENZYME ACTIVITY 1. TEMPERATURE :- Enzyme works at optimum temperature (35-40˚C). -At high temperature denaturation of enzymes occur. -Lower temperature inactivates the enzyme. Enzyme activity Temp pH 40 0 C Enzymes are denatured beyond 40 O C

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2. Ph :- Enzymes require optimum ph. Some work at neutral ph, some at acidic ph(protease), & some at alkaline ph(amylase). Enzyme activity pH pH Could be protease (found in the stomach) Could be amylase (found in the intestine) 3. SUBSTRATE CONCENTRATION :- Due to high conc. Of substrate , enzyme achieves max. catalysation rate. -but under high substrate conc. it gets saturated & substrate conc no longer affects enzyme activity .

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4. INHIBITORS :- Molecular agents that slow down or halts the enzymatic reaction. 3 types of inhibitors 1. COMPETITIVE INHIBITORS :- Are chemicals that resemble enzymes normal substrate & compete with it for enzymes active site. Enzyme Competitive inhibitor Substrate

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2. NON-COMPETITIVE INHIBITORS :- They do not enter active site, but bind to another part of the enzyme (allosteric site) causing the enzyme to change its shape. Enzyme Noncompetitive Inhibitor active site altered Substrate 3. UNCOMPETITIVE INHIBITORS :- They bind at a site distinct from the substrate active site & they bind only to the ES complex.

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TYPES OF ENZYMES 6 TYPES 1. OXIDOREDUCTASE :- They are involved in redox rxn i.e transfer of hydrogen or oxygen atoms b/w molecules. - Includes dehydrogenase (hydride transfer) , oxidases ( e‐ transfer to O2) , oxigenases & peroxidases ( e̵ transfer to peroxidase ) Eg :- Alcohol dehydrogenase , converts primary alcohols into aldehydes CH 3 CH 2 OH + NAD → CH 3 CHO + NADH + H +

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2.GROUP TRANSFER REACTION :- These enzymes called transferases , move functional group from one molecule to another. For example, alanine aminotransferase shuffles the alpha-amino group between alanine and aspartate : Other transferases move phosphate groups between ATP and other compounds, sugar residues to form disaccharides and so on.

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3.HYDROLYSIS :- These enzymes termed hydrolases , break single bond by adding the elements of water. For eg :- Phosphatases break the oxygen-phosphorous bond of phosphate ester: O O + ║ H 2 O ║ R−O─P─Oˉ → R─OH + HO−P─Oˉ | | Oˉ Oˉ -Other hydrolases function as digestive enzymes, eg breaking of peptide bonds in proteins.

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4.FORMATION OR REMOVAL OF DOUBLE BOND WITH GROUP TRANSFER :- The functional groups tranferred by lyase enzymes include amino groups, water and ammonia. For eg :- a.) Dehydratases remaove water as in fumarase ( fumarate hydratase ) COˉ 2 COˉ2 | | CH HO─C─H ║ | HC H─C─H | | COˉ 2 COˉ2

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b.) Deaminases remove ammonia, For eg :-removal of amino groups from aminoacids COˉ 2 COˉ2 + | | H3N─ C─H → CO + NH3 | | CH2OH CH3 Serine Pyruvate c.) Decarboxylases remove co2 from alpha- or beta- keto acids.

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5. ISOMERISATION OF FUNCTIONAL GROUPS :- In many biochemical reactions, the position of a functional group is changed within a molecule, but the molecule itself contains the same number and kind of atoms that it did in the beginning. In other words, the substrate and product of the reaction are isomers. The isomerases , For example, triose phosphate isomerase , shown following carry out these rearrangements.

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+ H3N | O tRNAgly─OH + ATP + H2C ─C ─C Oˉ O ║ NH3+ tRNAgly─O─C ── CH2 + AMP + O O ║ ║ Oˉ─ P─ O ─ P ─Oˉ | | Oˉ Oˉ

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IMMOBILISATION OF ENZYMES It is the process of fixing an enzyme by physical or chemical means to a solid support– eg a bead or gel to confine a reaction of interest to a particular site . The material used for immobilization of enzymes is called carrier matrices( clays, glasses,etc ) METHODS OF IMMOBILIAZATION ADSORPTION :- Similar to physical adsoption . - Mix the enzyme with a suitable adsorbent. - Incubate. - Wash off loosley bound/unbound enzyme. Adv . ● Easy & cheap ● Enzyme activity unaffected Disadv. ● Desorption of enzyme due to change in temp & Ph .

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2. COVALENT BINDING :- Attachment is through covalent bonds. - The bond formation occurs with the side chain of amino acid of the enzyme - Commonly used matrices are agarose, celluloses, etc. - Lysine residue are most useful in covalent binding. 3. ENTRAPMENT :- Enzyme molecules are held or entrapped within suitable gels or fibers. - There may or may not be covalent bond formation - Non covalent entrapment may be viewed as putting enzyme in a molecular cage. - Calcium alginate is most commonly used for entrapment. Adv . ● Strong bonds are formed. Disadv .● Enzyme loading is low. Adv ● Enzyme loading is high. Disadv . ● Enzyme leakage into solution.

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4. MEMBRANE CONFINEMENT :- Enzyme molecules ( in aq sol.) are confined in semi- permeable membrane which allows free movement of substrate & products but not of enzymes. Diff strategies employed are : - Vessel partioned by semi-permeable membrane having product & substrate in diff & enzyme in diff chamber. - Enzymes may be packed in microcapsules or in liposomes . Adv ● Strong binding force. Disadv ● High cost. ADV. OF IMMOBILIZATION DISADV. OF IMMOBILIZATION → Easy separation from rxn mixtures. → Re-use of enzymes → Enzymes provide pure products. → Thermo stability of some enzymes inc. → High cost of production. → Affects the activity of enzymes. → Immobilization cannot be done if the substrate is insoluble. → Chances of contamination is high & therefore antibiotic should be used.

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USES OF ENZYMES ● DETERGENTS :- ( i ) Proteases are used to digest milk, grass stains. (ii) α –amylase & cellulase used for washing cotton fabrics. ● LEATHER INDUSTRY :- Alkaline protease are used to remove hair from hides; this is safer & pleasant than the traditional method of using sodium sulfide. ● MEDICINES :- ( i ) Lysozyme causes bacterial cell wall hydrolysis & is used as antibiotic. (ii) Collagenase is used for collagen hydrolysis & hence treats skin ulcers. (iii) Urokinase converts plasminogen to plasmin & removes clot, etc.

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THANKS