enzyme and enzyme kinetics

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  • PAMANTASAN NG LUNGSOD NG MAYNILA

    College of Engineering and Technology

    Chemical Engineering Department

    CHE 512 Biochemical Engineering

    A WRITTEN REPORT

    ENZYME AND ENZYME KINETICS

    Submitted by: BESA, Rose Lynn Anne DARANCIANG, Erish

    DECAPIA, Handrey LUDOVICE, Bianca Jamila

    BSChE 5

    Submitted to: Engr. Elaine G. Mission

  • Page 2 of 37

    Contents ENZYME ......................................................................................................................................................... 3

    Brief History of Enzyme ............................................................................................................................. 3

    Enzyme Classification and Nomenclature ................................................................................................. 4

    Common Enzymes ..................................................................................................................................... 9

    pH of some Enzymes ............................................................................................................................... 10

    Industrial Applications ............................................................................................................................ 11

    Factors affecting Enzyme Activity ........................................................................................................... 13

    SIMPLE ENZYME KINETICS........................................................................................................................... 16

    Introduction to Enzyme Kinetics ............................................................................................................. 16

    Rate of Reaction .................................................................................................................................. 16

    Formation of Enzyme-Substrate Complex ........................................................................................... 18

    Lock-and-Key Theory ........................................................................................................................... 18

    Induced-Fit Model ............................................................................................................................... 18

    Michaelis-Menten Kinetic Model ............................................................................................................ 19

    Biographies of Michaelis and Menten ................................................................................................ 22

    Derivation of Rate Equation (Michaelis-Menten equation) ................................................................ 23

    Biographies of Lineweaver and Burk ................................................................................................... 25

    Graphical Analysis ............................................................................................................................... 26

    ENZYME REACTOR WITH SIMPLE KINETICS ................................................................................................. 31

    General Types of Bioreactors .................................................................................................................. 32

    Batch Stirred-Tank Reactor .................................................................................................................. 32

    Plug-Flow Reactor ............................................................................................................................... 33

    Continuous Stirred-Tank Reactor ........................................................................................................ 34

    ENZYME INHIBITION ................................................................................................................................... 36

    Bibliography ................................................................................................................................................ 37

  • Page 3 of 37

    ENZYME

    Enzymes are biological catalysts. They increase the rate of chemical reactions taking place within living

    cells without themselves suffering any overall change. The reactants of enzyme-catalyzed reactions are

    called substrates. Each enzyme is quite specific in character, acting on a particular substrate or substrates

    to produce a particular product.

    All known enzymes are proteins. They therefore consist of one or more polypeptide chains and display

    properties that are typical of proteins. Some enzymes require small non-protein molecules, known as

    cofactors, in order to function as catalysts.

    Enzymes differ from chemical catalysts in several important ways:

    1. Enzyme-catalyzed reactions are at least several orders of magnitude faster than chemically-

    catalyzed reactions. When compared to the corresponding unanalyzed reactions, enzymes

    typically enhance the rates by 106 to 1013 times.

    2. Enzymes have far greater reaction specificity than chemically-catalyzed reactions and they rarely

    form byproducts.

    3. Enzymes catalyze reactions under comparatively mild reaction conditions, such as temperatures

    below 100C, atmospheric pressure and pH around neutral. Conversely, high temperatures and

    pressures and extremes of pH are often necessary in chemical catalysis.

    Brief History of Enzyme

    1833 The active agent breaking down the sugar was partially isolated and given the name

    distase (now known as amylase). A little later, a substance which digested dietary protein

    was extracted from gastric juice and called pepsin. These and other active preparations

    were given the general name ferments. Justus von Liebig recognized that these ferments

    could be non-living materials obtained from living cells, but Louis Pasteur still maintained

    that ferments must contain living material.

    1878 The term ferment was gradually replaced by the name enzyme which is proposed by

    Wilhelm Kuhne. It comes from a Greek enzume, meaning in yeast.

    1897 Brothers Eduard and Hans Buchner showed that sugar fermentation could take place

    when a yeast cell extract was added even though no living cells were present.

    1926 James Sumner crystallized urease from jack-bean extracts and in the next few years, many

    other enzymes were purified and crystallized.

  • Page 4 of 37

    Enzyme Classification and Nomenclature

    Enzymes are classified according to the report of the Nomenclature Committee appointed by the

    International Union of Biochemistry (1984). This enzyme commission assigned each enzyme a

    recommended name and a four-part distinguishing number.

    The first Enzyme Commission, in its report in 1961, devised a system for classification of enzymes that also

    serves as a basis for assigning code numbers to them. These code numbers, prefixed by EC, which are now

    widely in use, contain four elements separated by points, with the following meaning:

    1. The first number shows to which of the six main classes the enzyme belongs,

    2. The second figure indicates the type of group involved in the reaction,

    3. The third figure denotes the reaction by indicating substrate on which the group acts,

    4. The fourth figure is the serial number of the enzyme in its sub-subclass.

    Class 1. Oxidoreductases

    To this class belong all enzymes catalysing redox reactions. The substrate that is oxidized is regarded as

    hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The common name will

    be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used

    in cases where O2 is the acceptor.

    2nd EC digit: indicates group in the hydrogen donor (substrate oxidized)

    The six main classes of enzymes

  • Page 5 of 37

    3rd EC digit: indicates type of acceptor involved

    Example:

    Code number: EC 1.1.1.27

    Systematic name: (S)-lactate: NAD+ oxidoreductase

    Common name: Lactate dehydrogenase

    Class 2. Transferases

    Transferases are enzymes transferring a group, e.g. a methyl group or a glycosyl group, from one

    compound (generally regarded as donor) to another compound (generally regarded as acceptor). The

    systematic names are formed according to the scheme donor:acceptor group transferase. The common

    names are normally formed according to acceptor group transferase or donor group transferase. In many

    cases, the donor is a cofactor (coenzyme) charged with the group to be transferred.

    2nd EC digit: indicates group transferred

    3rd EC digit: further information on group transferred

  • Page 6 of 37

    Example:

    Code number: EC 2.7.1.1

    Systematic name: ATP: D-hexose-6-phosphotransferase

    Common name: Hexokinase

    Class 3. Hydrolases

    These enzymes catalyze the hydrolytic cleavage of C-O, C-N, C-C and some other bonds, including

    phosphoric anhydride bonds. Although the systematic name always includes hydrolase, the common name

    is, in many cases, formed by the name of the substrate with the suffix -ase. It is understood that the name

    of the substrate with this suffix means a hydrolytic enzyme.

    2nd EC digit: indicates nature of bond hydrolysed

    3rd EC digit: indicates nature of substrate

    Example:

    Code number: EC 3.1.3.1

    Systematic name: Orthophosphoric monoester phosphohydrolase

    Common n

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