ENZYMES Flashcards
-Most are protein in nature
-Are proteins that act as catalyst in biochemical reactions
-Most efficicient catalysts
ENZYMES
❑“Table Sugar”
❑Disaccharide composed of an alpha-D-glucose molecule + beta D-Fructose
molecule linked by alpha-1,4-glycosidic bond
❑When this bond is cleaved in a hydrolysis reaction, an equimolar mixture of
glucose and fructose are generated – INVERT SUGAR
SUCROSE
When this bond is cleaved in a hydrolysis reaction, an equimolar mixture of
glucose and fructose are generated
INVERT SUGAR
❑“Beta-Fructofuranosidase
❑Mainly used in the food (confectionery) industry
❑Commercially invertase is biosynthesized by yeast strains of
Saccharomyces cerevisiae or Saccharomyces carlsbergensis.
INVERTASE
❑Sugars capable of acting reducing agents because it
has a free aldehyde group or a ketone group.
REDUCING SUGARS
REDUCING
SUGARS
Glucose Sucrose
Fructose
Lactose
Maltose
Galactose
NON REDUCING
SUGARS
Sucrose
Glucose + Fructose
Sucrose
Galactose + Glucose
Lactose
Glucose + Glucose
Maltose
❑3,5-Dinitrosalicylic Acid or 2- hydroxy-3,5-Dinitrobenzoic acid
❑An aromatic compound that reacts with reducing sugars and other
reducing molecules to form 3-amino 5-nitrosalicylic acid
❑Strongly absorbs light at 540 nm
DNS
❑ Detects the presence of free carbonyl
group (C=O) of reducing sugars
❑ It involves the oxidation of the
aldehyde functional group in Glucose
and Ketones functional groups in
Fructose.
DNS COLORIMETRIC METHOD
3,5-dinitrosalicylic acid (yellow)
reduction
————->
3 amino, 5-nitro salicylic acid (orange-red)
the most favorable pH values- the point
where the enzymes is most active
Optimum pH
pH for optimum Activity
Enzymes
Lipase (pancreas)=8.0
Lipase (stomach)= 4.0 – 5.0
Lipase (castor oil)= 4.7
Pepsin =1.5 – 1.6
Trypsin =7.8 – 8.7
Urease= 7.0
Invertase= 4.5
Maltase =6.1 – 6.8
Amylase (pancreas) =6.7 – 7.0
Amylase (malt) =4.6 – 5.2
Catalase =7.0
Lipase (pancreas)
8.0
lipase (stomach)
4.0-5.0
Lipase (castor oil)
4.7
Pepsin
1.5-1.6
trypsin
7.8-8.7
Urease
7.0
invertase
4.5
Maltase
6.1-6.8
Amylase (pancreas)
6.7-7.0
Amylase (malt)
4.6-5.2
Catalase
7.0
Effects of temperature on reaction rate
the rate of reaction increases when the temperature increases
❑The reaction rate increases with temperature to a maximum level,
then abruptly decline with further increase of temperature
❑Most of the enzymes rapidly become denatured at temperature
above 40 C
❑Storage of enzymes at 5 C or below is generally the most suitable
EFFECTS OF TEMPERATURE
