Enzymes as biocatalysts Use of exogeneous enzymes

1. ENZYMES AS BIOCATALYSTS
&
USE OF EXOGENEOUS ENZYMES(
CARBOHYDRATE AND LIPID-TRANSFOMING
ENZYMES)
AVNEET KAUR
317006
FSQM

2. ENZYMES
 Proteins functioning as catalysts that speed up
reactions by lowering the activation energy.
Has important traits:
 are proteins
 are catalysts
 exhibit selectivity towards substrates.
 Enzymes are specific.
Enzymes provide a specific environment within which a
given reaction is energetically more favorable.

3. MECHANISMS OF ENZYMATIC CATALYSIS
 Substrate is changed into product via high energy
transition state.
E + S ES
ES E + P

4.  Active sites: clefts or grooves, composed of amino acids
from different parts of the polypeptide .
 Co-factor: non protein molecule which carries out
chemical reactions that can not be performed by standard
20 amino acids.
 Substrate: reactant in biochemical reaction.
 Inhibitors: decrease the rate of enzyme-catalyzed
reactions. Can be competitive(Structurally similar inhibitor
and substrate bind to the same site) or non-
competitive(bind non-covalently and reversibly at the sites
other than the active site).

5. MICHAELIS-MENTEN EQUATION

6. MODELS OF ENZYME –SUBSTRATE
INTERACTION

7. FACTORS AFFECTING ACTIVITY
Temperature
Enzyme
concentration
Surface area Pressure
Substrate
concentration
pH

8. EXOGENEOUS ENZYMES
 Enzymes which are present in raw, uncooked food are
called food enzymes to indicate where they come from:
the food itself.
 Uses:
• glucose, HFCS
production of food commodities
• beer stabilization, meat tenderization
modification of components
• cheese ripening, juice extraction, faster dough mixing
process improvement

9. CARBOHYDRATE-TRANSFORMING
ENZYMES
 Most enzymes are hydrolytic and are collectively referred
to as glycosyl hydrolases or glycosidases.
 accounts for about half of enzyme use as processing aids
in the food industry.
 functions by either general acid–base catalysis and/or
nucleophilic catalysis.
 Types (based on the fate of the anomeric configuration
(α or β) of the hydrolyzed glycosidic bond)
“retaining” or “inverting”,

11. STARCH-TRANSFORMING ENZYMES
α-Amylase
• Hydrolyze
starch into
smaller dextrins
• Make “thin”
starch
suspensions
• Has three
separate
domains
(catalysis,
granular starch
binding site, and
for calcium
binding)
β-Amylase
• exoenzyme that
releases
successive
maltose units
from the
nonreducing
end of a
polysaccharide
chain by
hydrolysis of α-
1,4-glucan
linkages.
Glucoamylase
• produce
glucose from
starch
• Uses : in
alcohol
production,
baking, dental
hygiene, fruit
juicing
• Hydrolyzes 1,4-
α-D-glucose
residues

12. Applications of these include
 starch hydrolyses,
 bakery industry and
 brewery and fermentation.

13. SUGAR TRANSFORMATION AND
APPLICATIONS
• Xylose (glucose) isomerase – used in sweetener
production
Glucose Isomerization
• Glucose oxidase obtained from Aspergillus niger.
• Removes oxygen in liquids or within packages, or
generating gluconic acid.
Glucose Oxidation
• production of soft-centered confections and to produce
artificial honey from sucrose.
Sucrose Hydrolysis (Inversion)

14. LIPID-TRANSFORMING ENZYMES
Lipase:
Act only at the oil–water interface. liberates flavoring
(short-chain) fatty acids from lipids and rearranges
fatty acyl groups along the glycerol backbone.
 Used in flavour generation, for example in enzyme
modified cheeses.
 Helps in preparation of structured lipids.
 Added as dough improvers, which manifests as
increased bread volume, more uniform crumb and
air cell size.

15. Lipoxygenases:
Generally considered to have detrimental effects. One
beneficial use of is to provide oxidizing power during
dough conditioning.
 oxidizes unsaturated fatty acids generating oxidizing
conditions that help strengthen the gluten network by
affecting disulfide cross-links within the gluten.
 Secondary oxidation reactions -destroy endogenous
carotenoids.

16. Phospholipases:
types: A1, A2, C, and D.
 PhospholipaseA2 has potential use as an agent to create
superior lysophospholipid emulsifiers from phospholipid-
rich sources, such as egg yolk.
 Added to crude oil during degumming stage to hydrolyze
phospholipids at the sn-2. Important for the removal of
otherwise nonhydratable phospholipids.

17. THANK YOU!