Immobilize Enzyme System Flashcards
The restriction of enzyme mobility in a fixed space is known as ______. This provides important advantages,
such as enzyme reutilization and elimination of enzyme recovery and purification processes, and may provide a better environment for enzyme activity.
Enzyme Immobilization
Since enzymes are expensive,
this is critical for many
processes.
Catalyst-reuse
is the physical enclosure of enzymes in a small space.
Entrapment
Major methods of Entrapment
Matrix entrapment and Membrane entrapment
used for enzyme immobilization are usually
polymeric materials such as Ca-alginate, agar, k-carrageenin, polyacrylamide, and collagen. However, some solid such as activated carbon, porous ceramic, and diatomaceous earth can also be
used for this purpose.
Matrices
it can be a particle, a
membrane, or a fiber.
Matrix
is either extruded or a template is used to shape the particles from a liquid polymer-enzyme mixture.
Polymerized gel-containing enzyme
entrapment of enzymes
is possible; for example, hollow
fiber units have been used to
entrap an enzyme solution
between thin, semipermeable
membranes.
Membrane Entrapment
A special form of membrane
entrapment is _______. In this technique, microscopic
hollow spheres are farmed. The
spheres contain the enzyme
solution, while the sphere is
enclosed within a porous
membrane. The membrane can be polymeric or an enriched
interfacial phase formed around a microdrop.
Microencapsulation
can be overcome by reducing the MW cutoff of membranes or the pore size of solid matrices.
Enzyme Leakage
can be eliminated by reducing the particle size of matrices and/or capsules.
Diffusion Limitation
are due to unfavorable
microenvironmental conditions,
which are difficult to control.
However, by using different
matrices and chemical ingredients, by changing processing conditions, and by reducing particle or capsule size, more favorable microenvironmental conditions can be obtained.
Reduced enzyme activity and
stability
is usually less significant in microcapsules as compared to gel beads.
Diffusion Barrier
The two major types of
immobilizations of enzymes on the surfaces of support materials are
Adsorption and Covalent Binding
is the attachment of
enzymes on the surfaces of support particles by weak physical forces, such as van der Waals or dispersion forces
Adsorption
is a common problem, especially in the presence of strong hydrodynamic forces, since binding forces are weak.
desorption of enzymes
The _______ of the adsorbed
enzyme is usually unaffected, and nearly full activity is retained upon adsorption.
Active Site
Adsorption of enzymes may be
stabilized by cross-linking with “blank”. “Blank” treatment can denature some proteins.
Glutaraldehyde
is the retention of enzymes on support surfaces by covalent bond formation.
Covalent Binding
Enzyme molecules bind to support material via certain “blank”, such as amino, carboxyl, hydroxyl, and sulfhydryl groups.
functional groups
These functional groups must not be in the
Active Site
Functional groups on support
material are usually activated by using “blank”, such as
cyanogen bromide, carbodiimide, and glutaraldehyde.
Chemical Reagent
One common trick Is to block the active site by flooding the enzyme solution with a “blank” prior to covalent binding.
Competitive Inhibitor
This may cause significant changes in the active
site of enzymes, and also severe diffusion limitations may result.
Cross-linking
Two major criteria used in the
selection of support material
(1) the binding capacity of the
support material, which is a are
function of charge density,
functional groups, porosity, and
hydrophobicity of the support
surface,
and (2) stability and retention of enzymatic activity, which is a function of functional groups on support material and
microenvironmental conditions.
If immobilization causes some conformational changes on the enzyme, or if
reactive groups on the active site of the enzyme are involve in binding, a “blank” in
enzyme activity can take place upon immobilization.
Loss
it may be more advantageous to use “blank” with the desired enzyme activity in Immobilized form. This approach eliminates costly enzyme separation and purification steps and is therefore economically more feasible.
inactive (dead or resting) cells
are produced by using
overproducing strains of Bacillus, Aspergillus, Rhizopus, and Mucor
Proteases
are produced by Aspergillus niger, lactases are produced by yeast and Aspergillus;
Pectinases
are produced by certain
strains of yeasts and fungi;
Lipases
is produced by Flavobacterium arborescens or Bacillus coagulans.
Glucose Isomerace
If enzyme release is not complete, then “blank” may be essential.
Cell Disruption
Intracellular enzymes may be
released by increasing the
permeability of cell membrane.
Certain salts such as “blank” and other chemicals such as “blank” and pH shift may be used for this purpose.
CaCl₂
dimethylsulfoxide (DMSO)
hydrolyze proteins into
smaller peptide units and
constitute a large and industrially important group of enzymes:
Proteases
Most of the industrial proteases are
Endoproteases
are used in food
processing, such as cheese making (rennet), baking, meat
tenderization (papain, trypsin),
and brewing (trypsin, pepsin); in detergents for the hydrolysis of protein stains (subtilisin
Carlsberg); and in tanning and the medical treatment of wounds.
Proteases
are used in fruit juice
processing and wine making to
increase juice yield, reduce
viscosity, and clear the juice.
Pectinases
may be used to hydrolyze oils for soap manufacture and to hydrolyze the lipid-fat compounds present in waste-water streams.
Lipases
-1.6 glycosidic linkages in the amylopectin fraction of starch are hydrolyzed by
“glucoamylase”, which is also known as a
saccharifying enzyme.
A -amylase breaks a -1,4 glycosidic bonds randomly on the amylose chain and
solubilizes amylose. For this reason, a-amylase is known as the
starch liquefying enzyme
are used in cereal processing, alcohol fermentation from biomass, brewing, and waste treatment.
Cellulases
are used in combination with other enzymes in baking doughs, brewing mashes, alcohol fermentation from biomass, and waste treatment.
Hemicellulases
are used in the fermentation of cheese. And are used to hydrolyze lactose in when to glucose and galactose
Lactases
is used by the antibiotic industry to convert penicillin G to 6-aminopenicillanic acid (6-APA), which is a precursor for semisynthetic penicillin
derivatives.
Penicillin Acylases
The conversion of glucose to fructose by immobilized “blank” is an important industrial process. Fructose is nearly 1.7 times sweeter than glucose and
is used as a sweetener in softdrinks.
Glucose Isomerace
can be used as an anti-inflammatory agent, lysozyme which hydrolyzes the
cell wall of gram-positive bacteria, is used as an antibacterial agent.
Trypsin
is used as an anti-inflammatory agent. aside from Trypsin
Streptokinase
is used in dissolving and preventing blood clots.
Urokinase
is used as an anticancer agent.
Asparaginase
is used for the determination of glucose levels in blood and urine.
Glucose Oxidase
hydrolyze penicillin and are used to treat allergic reactions against penicillin.
Penicillinases
are used in the dissolution of blood clots (particularly following a heart
attack or stroke).
Tissue plasminogen activator
(TPA) and streptokinase
