BioChem Lab Flashcards
enzymes
-most are protein in nature
-proteins that act as catalyst in biochemical reactions
-most efficient catalyst
sucrose
-table sugar
-disaccharide composed of an alpha-d-glucose + beta d-fructose molecule linked together by alpha-1,4-glycosydic bond
invert sugar
when the bond is cleaved in a hydrolysis reaction, an equimolar mixture of glucose and fructose are generated
invertase
beta-fructofuranosidase
mainly used in the food (confectionary) industry
commercial invertase is biosynthesized by yeast strains of saccharomyces cerevisiae or saccharomyces carlsbergensis
reducing sugars
capable of acting reducing agents because it has a free aldehyde group or a ketone group
reducing sugars
Glucose
Fructose
Lactose
Maltose
Galactose
non reducing sugars
sucrose
DNS
-3,5-dinitrosalicylic acid or 2-hydroxy-3,5-dinitrobenzioc acid
-an aromatic compound that reacts with -reducing sugars and other reducing -molecules to form 3-amino-5-nitrosalicylic acid
-strongly absorbs light at 540nm
DNS colorimetric method
-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
Effects of pH
optimum pH- the most favorable pH values- the point where the enzymes is most effective
enzymes optimum pH
enzymes optimum pH
lipase (pancreas) 8.0
lipase (stomach) 4.0- 5.0
lipase (castor oil) 4.7
amylase (pancreas) 6.7- 7.0
amylase (malt) 4.6- 5.2
pepsin 1.5- 1.6
trypsin 7.8- 8.7
urease 7.0
catalase 7.0
invertase 4.5
maltase 6.1- 6.8
effects of temperature
-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 40degC
-storage of enzymes at 5degC or below is generally the most suitable
catalysts
-a substance that can be added to a reaction to increase the reaction rate without getting consumed in the process
-it typically speed up a reaction by reducing the activation energy or changing the reaction mechanism
A- simple enzyme
active site
substrate
enzyme
B- holoenzyme
made up of protein groups (apoenzyme) and non protein component (cofactor)
Co-factors
organic (co-enzymes)
non-organic (activators)
prosthetic group
organic co-enzymes
vitamins
B2: FAD FADH2 (flavine adenine dinucleotide)
B3: NAD NADH (nicotinamide adenine dinucleotide)
B5: CoA (acetyl co-enzyme)
non-organic activators
metals:
K+
Ca+2
Mn+2
Co+2
-the main or product of the active structural conformation of the enzyme
-promote the formation of enzyme-substrate complex
-acting as e-donors or acceptors cause distortions in the substrate or the enzyme
prosthetic groups
cofactor that is bound so tightly to the apoenzyme and is difficult to remove without damaging the enzyme
C- allosteric sites
binding can increase (allosteric activation) or decrease (allosteric inhibition) the affinity to the substrate
properties and characteristics of enzymes
-catalyze biological and reactions
-can speed up reaction to go a million or billion faster
-rate of reaction is dependent to enzyme reaction
-the max velocity of an enzyme reaction is proportional to its concentration
-enzymes are substrate specific
-enzymes are very sensitive to pH and temperature
theories of bonding
1- lock and key- exact (rigid) specific bonding
2- induced fit- flexible bonding