tugas 2 biokatalisis
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1. Difference between catalyst and biocatalyst:No Criteria Catalyst Biocatalyst
1
Function:
Catalysts are substances that
increase or decrease the rate ofa chemical reaction but remain
unchanged.
Enzymes are proteins that
increase rate of chemicalreactions converting substrate
into product.
2Molecular weight:
Low molecular weight
compounds.
High molecular weight
globular proteins.
3
Types:
There are two types of
catalysts positive and
negative catalysts.
There are two types of
enzymes - activation enzymes
and inhibitory enzymes.
4Nature:
Catalysts are simple inorganic
molecules.Enzymes are complex proteins.
5
Alternate terms: Inorganic catalyst.
Organic catalyst or bio-
catalyst.
6Reaction rates: Typically slower Several times faster
7
Specificity:
They are not specific and
therefore end up producing
residues with errors
Enzymes are highly specific
producing large amount of
good residues
8Conditions: High temperature and pressure
Mild conditions, physiological
pH and temperature
9C-C and C-H bonds: Absent Present
10Example:
Vanadium oxide, Manganesedioxide, Sulfuric Acid, Zeolite
Hydrolase, transferase,isomerase, ligase,
oxidoreductase, lyase.
11Activation Energy: Lowers it Lowers it
12Price: Low, quite affordable High
13Endurance: High endurance Easily denaturized
2.
Difference between batch and continuous reactor:
No Criteria Batch Reactor Continuous Reactor
1 Cost of factory
equipment:
High Low
2 Rate of production: High Low
3 Shut-down times: Rare Often
4 Workforce: Few people needed Many people needed
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5 Ease of automation: Relatively easy Relatively difficult
6 Production: Product needed in a small
amount or only as needed (a
speciality chemical),
production does not go on allthe time.
Product needed in a large amount,
production goes all the time.
7 Example: Pharmaceutical drugs
(medicines)
Ammonia (Haber process).
3. What is Dalton?The unified atomic mass unit (symbol: u) or dalton (symbol: Da) is the standard
unit that is used for indicating mass on an atomic or molecular scale (atomic
mass). One unified atomic mass unit is approximately the mass of a nucleon and is
equivalent to 1 g/mol It is defined as one twelfth of the mass of an unbound
neutral atom of carbon-12 in its nuclear and electronic ground state and has a
value of 1.660538921(73)1027 kg.
1 u or Da is equal to...Kg 1.660538921(73)1027eV/c2 931.494061(21)106me 1822.88839mp 7.6293610
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4. Types of enzyme inhibitor:a. Irreversible inhibitors: Irreversible inhibitors usually covalently modify an
enzyme, and inhibition can therefore not be reversed. Irreversible inhibitors
often contain reactive functional groups such as nitrogen mustards, aldehydes,
haloalkanes, alkenes, Michael acceptors, phenyl sulfonates, or
fluorophosphonates. These electrophilic groups react with amino acid sidechains to form covalent adducts. The residues modified are those with side
chains containing nucleophiles such as hydroxyl or sulfhydryl groups; these
include the amino acids serine (as in DFP, right), cysteine, threonine or
tyrosine. Irreversible inhibition is different from irreversible enzyme
inactivation. Irreversible inhibitors are generally specific for one class of
enzyme and do not inactivate all proteins; they do not function by destroying
protein structure but by specifically altering the active site of their target. For
http://en.wikipedia.org/wiki/Covalenthttp://en.wikipedia.org/wiki/Nitrogen_mustardhttp://en.wikipedia.org/wiki/Aldehydehttp://en.wikipedia.org/wiki/Haloalkanehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Michael_acceptorhttp://en.wikipedia.org/wiki/Sulfonatehttp://en.wikipedia.org/wiki/Methoxy_arachidonyl_fluorophosphonatehttp://en.wikipedia.org/wiki/Electrophilehttp://en.wikipedia.org/w/index.php?title=Covalent_adducts&action=edit&redlink=1http://en.wikipedia.org/wiki/Nucleophilehttp://en.wikipedia.org/wiki/Hydroxylhttp://en.wikipedia.org/wiki/Thiolhttp://en.wikipedia.org/wiki/Serinehttp://en.wikipedia.org/wiki/Diisopropylfluorophosphatehttp://en.wikipedia.org/wiki/Cysteinehttp://en.wikipedia.org/wiki/Threoninehttp://en.wikipedia.org/wiki/Tyrosinehttp://en.wikipedia.org/wiki/Protein_structurehttp://en.wikipedia.org/wiki/Protein_structurehttp://en.wikipedia.org/wiki/Tyrosinehttp://en.wikipedia.org/wiki/Threoninehttp://en.wikipedia.org/wiki/Cysteinehttp://en.wikipedia.org/wiki/Diisopropylfluorophosphatehttp://en.wikipedia.org/wiki/Serinehttp://en.wikipedia.org/wiki/Thiolhttp://en.wikipedia.org/wiki/Hydroxylhttp://en.wikipedia.org/wiki/Nucleophilehttp://en.wikipedia.org/w/index.php?title=Covalent_adducts&action=edit&redlink=1http://en.wikipedia.org/wiki/Electrophilehttp://en.wikipedia.org/wiki/Methoxy_arachidonyl_fluorophosphonatehttp://en.wikipedia.org/wiki/Sulfonatehttp://en.wikipedia.org/wiki/Michael_acceptorhttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Haloalkanehttp://en.wikipedia.org/wiki/Aldehydehttp://en.wikipedia.org/wiki/Nitrogen_mustardhttp://en.wikipedia.org/wiki/Covalent -
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example, extremes of pH or temperature usually cause denaturation of all
protein structure, but this is a non-specific effect.
Figure 1. Kinetic scheme for irreversible inhibitors
Examples: nerve gases and pesticides, containing organophosphorus, combine
with serine residues in the enzyme acetylcholine esterase.
b. Reversible inhibitors: Reversible inhibitors bind to enzymes with non-covalent interactions such as hydrogen bonds, hydrophobic interactions and
ionic bonds. Multiple weak bonds between the inhibitor and the active site
combine to produce strong and specific binding. In contrast to substrates andirreversible inhibitors, reversible inhibitors generally do not undergo chemical
reactions when bound to the enzyme and can be easily removed by dilution or
dialysis. There are four kinds of reversible enzyme inhibitors. They are
classified according to the effect of varying the concentration of the enzyme's
substrate on the inhibitor.
Competitive inhibition, the substrate and inhibitor cannot bind to theenzyme at the same time, as shown in the figure on the left. This usually
results from the inhibitor having an affinity for the active site of an enzyme
where the substrate also binds; the substrate and inhibitor compete for
access to the enzyme's active site. This type of inhibition can be overcome
by sufficiently high concentrations of substrate (Vmax remains constant),
i.e., by out-competing the inhibitor. However, the apparent Km will
increase as it takes a higher concentration of the substrate to reach the Km
point, or half the Vmax. Competitive inhibitors are often similar in
structure to the real substrate (see examples below).
http://en.wikipedia.org/wiki/Denaturation_(biochemistry)http://en.wikipedia.org/wiki/Protein_structurehttp://en.wikipedia.org/wiki/Hydrogen_bondhttp://en.wikipedia.org/wiki/Hydrophobic_interactionhttp://en.wikipedia.org/wiki/Ionic_bondhttp://en.wikipedia.org/wiki/Substrate_(biochemistry)http://en.wikipedia.org/wiki/Competitive_inhibitionhttp://en.wikipedia.org/wiki/Active_sitehttp://en.wikipedia.org/wiki/File:Irreversible_inactivation2.svghttp://en.wikipedia.org/wiki/Active_sitehttp://en.wikipedia.org/wiki/Competitive_inhibitionhttp://en.wikipedia.org/wiki/Substrate_(biochemistry)http://en.wikipedia.org/wiki/Ionic_bondhttp://en.wikipedia.org/wiki/Hydrophobic_interactionhttp://en.wikipedia.org/wiki/Hydrogen_bondhttp://en.wikipedia.org/wiki/Protein_structurehttp://en.wikipedia.org/wiki/Denaturation_(biochemistry) -
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Competitive inhibition increases the apparent value of the Michaelis-
Menten constant, , such that initial rate of reaction, , is given
by
where , is the inhibitor's
dissociation constant and is the inhibitor concentration.
remains the same because the presence of the inhibitor can be
overcome by higher substrate concentrations. , the substrate
concentration that is needed to reach , increases with the
presence of a competitive inhibitor. This is because the concentration of
substrate needed to reach with an inhibitor is greater than the
concentration of substrate needed to reach without an
inhibitor.
Uncompetitive inhibition, the inhibitor binds only to the substrate-enzymecomplex, it should not be confused with non-competitive inhibitors. This
http://en.wikipedia.org/wiki/Michaelis-Mentenhttp://en.wikipedia.org/wiki/Michaelis-Mentenhttp://en.wikipedia.org/wiki/Uncompetitive_inhibitionhttp://en.wikipedia.org/wiki/Uncompetitive_inhibitionhttp://en.wikipedia.org/wiki/Michaelis-Mentenhttp://en.wikipedia.org/wiki/Michaelis-Menten -
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type of inhibition causes Vmax to decrease (maximum velocity decreases
as a result of removing activated complex) and Km to decrease (due to
better binding efficiency as a result of Le Chatelier's principle and the
effective elimination of the ES complex thus decreasing the Km which
indicates a higher binding affinity).
The LineweaverBurk equation states that:
Where v is the initial reaction velocity, Km is the MichaelisMenten
constant, Vmax is the maximum reaction velocity, and [S] is the
concentration of the substrate.
The LineweaverBurk plot for an uncompetitive inhibitor produces a line
parallel to the original enzyme-substrate plot, but with a highery-intercept,
due to the presence of an inhibition term :
http://en.wikipedia.org/wiki/Lineweaver%E2%80%93Burk_plothttp://en.wikipedia.org/wiki/Lineweaver%E2%80%93Burk_plothttp://en.wikipedia.org/wiki/Lineweaver%E2%80%93Burk_plothttp://en.wikipedia.org/wiki/Reaction_ratehttp://en.wikipedia.org/wiki/Michaelis%E2%80%93Menten_constanthttp://en.wikipedia.org/wiki/Michaelis%E2%80%93Menten_constanthttp://en.wikipedia.org/wiki/Michaelis%E2%80%93Menten_constanthttp://en.wikipedia.org/wiki/Michaelis%E2%80%93Menten_constanthttp://en.wikipedia.org/wiki/Concentrationhttp://en.wikipedia.org/wiki/Y-intercepthttp://en.wikipedia.org/wiki/Y-intercepthttp://en.wikipedia.org/wiki/Concentrationhttp://en.wikipedia.org/wiki/Michaelis%E2%80%93Menten_constanthttp://en.wikipedia.org/wiki/Michaelis%E2%80%93Menten_constanthttp://en.wikipedia.org/wiki/Reaction_ratehttp://en.wikipedia.org/wiki/Lineweaver%E2%80%93Burk_plot -
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Where [I] is the concentration of the inhibitor and Ki is an inhibition
constant characteristic of the inhibitor.
Mixed inhibition, the inhibitor can bind to the enzyme at the same time asthe enzyme's substrate. However, the binding of the inhibitor affects the
binding of the substrate, and vice versa. This type of inhibition can be
reduced, but not overcome by increasing concentrations of substrate.
Although it is possible for mixed-type inhibitors to bind in the active site,
this type of inhibition generally results from an allosteric effect where the
inhibitor binds to a different site on an enzyme. Inhibitor binding to this
allosteric site changes the conformation (i.e., tertiary structure or three-
dimensional shape) of the enzyme so that the affinity of the substrate for
the active site is reduced.
Non-competitive inhibition is a form of mixed inhibition where the bindingof the inhibitor to the enzyme reduces its activity but does not affect the
binding of substrate. As a result, the extent of inhibition depends only on
the concentration of the inhibitor. Vmax will decrease due to the inability
for the reaction to proceed as efficiently, but Km will remain the same as
the actual binding of the substrate, by definition, will still function
properly.
In the presence of a non-competitive inhibitor, the apparent enzyme affinity
is equivalent to the actual affinity. In terms of Michaelis-Menten kinetics,
Kmapp = Km. This can be seen as a consequence of Le Chatelier's
Principlebecause the inhibitor binds to both the enzyme and the enzyme-
substrate complex equally so that the equilibrium is maintained. However,
since some enzyme is always inhibited from converting the substrate to
product, the effective enzyme concentration is lowered. Mathematically,
http://en.wikipedia.org/wiki/Mixed_inhibitionhttp://en.wikipedia.org/wiki/Allosterichttp://en.wikipedia.org/wiki/Allosteric_sitehttp://en.wikipedia.org/wiki/Conformational_isomerismhttp://en.wikipedia.org/wiki/Tertiary_structurehttp://en.wikipedia.org/wiki/Non-competitive_inhibitionhttp://en.wikipedia.org/wiki/Enzyme_activityhttp://en.wikipedia.org/wiki/Michaelis-Menten_kineticshttp://en.wikipedia.org/wiki/Michaelis%E2%80%93Menten_kinetics#Michaelis_constant_KMhttp://en.wikipedia.org/wiki/Le_Chatelier%27s_Principlehttp://en.wikipedia.org/wiki/Le_Chatelier%27s_Principlehttp://en.wikipedia.org/wiki/Le_Chatelier%27s_Principlehttp://en.wikipedia.org/wiki/Le_Chatelier%27s_Principlehttp://en.wikipedia.org/wiki/Michaelis%E2%80%93Menten_kinetics#Michaelis_constant_KMhttp://en.wikipedia.org/wiki/Michaelis-Menten_kineticshttp://en.wikipedia.org/wiki/Enzyme_activityhttp://en.wikipedia.org/wiki/Non-competitive_inhibitionhttp://en.wikipedia.org/wiki/Tertiary_structurehttp://en.wikipedia.org/wiki/Conformational_isomerismhttp://en.wikipedia.org/wiki/Allosteric_sitehttp://en.wikipedia.org/wiki/Allosterichttp://en.wikipedia.org/wiki/Mixed_inhibition -
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