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  • Enzymes

    Enzymology: Study of enzymes is called enzymology.

    Enzyme: Enzymes are defined as: "Thermolabile biological catalysts which speed up a chemical reaction by lowering the activation energy without undergoing any change."

    Catalyst: Catalyst is a substance which speeds up the chemical reaction in non living things without undergoing any change. So enzymes are biological catalysts because they catalyze reactions in living things.

    Substrate: The substance on which enzyme act is called substrate.

    Discovery of enzymes: The word enzyme means " in yeast" because they were 1st discovered in an extract of yeast.

    Activation enzyme: The amount of energy required to activate the reactants so that they can react to form product is called activation enery
    or energy required to make substances react is called activation energy.
    Reactants must collide with a certain amount of energy in order to react, this critical level is called energy of activation. Normally the activation energy of reactants is high so the reactions are slow. Enzymes speeds up the chemical reaction by lowering the activation energy.

    Characteristics of enzymes:
    1. Enzymes are protein in nature.
    2. All enzymes three dimensional globular proteins.
    3. They are formed inside a living cell.
    4. Being proteins they are coded by DNA.
    5. Enzymes are biological catalysts.
    6. They are required in small quantity. An enzyme molecule can break down 100000 molecules/sec of other compounds.
    7. Enzymes are highly specific.
    8. Enzymes always catalyze a single reaction.
    Ex. Amylase only breaks the starch amylose.
    9. The functional specificity of every enzyme is the consequence of its specific chemistry and configuration.
    10. The reactions catalyzed by enzymes are reversible.

    The enzymes are larger than substrates but small part of enzyme called active site comes in contact with substrate where reaction takes place. Enzymes can work inside as well as outside the tissues.Enzymes can be studied both in vivo ( Living cell) and in vitro (Glass wares.Enzymes can be isolated and crystallized.. In crystal form enzymes are pure. Enzymes work with the help of co-enzymes.Enzymes are named by adding "ase" to the name of substrate.Ex: The enzyme that breaks cellulose is called cellulase. Enzymes can be used again and again because there is no change in enzyme before and after the chemical reaction.Enzymes require aqous medium for their activity.Most enzymes remain attached to organneles.