Enzyme Kinetics Flashcards
What factors affect enzyme activity?
- substrate concentration
- pH
- Temperature
- allosteric regulators
- covalent modification
- irreversible inhibition
- induction and repression
What is the function of Michaelis-Menten equation?
The Michealis-Menten equation describes the kinetic properties of many enzymes. It shows how the initial rate of a reaction, Vo depends on the substrate concentration [S]
What is table sugar?
Sucrose, a disaccharide composed of an alpha-D-glucose molecule and a beta-D-fructose molecule linked by an alpha-1,2-glycosidic bond
What is the function of invertase?
Sucrose can be hydrolyzed in the presence of an enzyme called invertase or sucrase
Sucrose + H2O —> glucose and fructose
What is another name for invertase?
The official name of invertase is beta-fructofuranosidase (EC3.2.1.26)
What is invert sugar?
When the bond is cleaved by invertase to an equimolar mixture of glucose and fructose is generated.
This mixture of monosaccharides is called invert sugar, which is derived from the fact that sucrose rotates plane polarized light to the right I.e., dextrorotatory, whereas the hydrolysis products rotates plane polarized light to the left I.e., levotatory
What industry mainly uses invertase?
Invertase is mainly used in the food (confectionary ) industry where the fructose is preferred over sucrose because it is sweeter and doesn’t crystallize as easily
However, the use of invertase is rather limited because another enzyme, glucose isomerase, can be used to convert glucose to fructose more inexpensively
What function does invertase for health and taste?
For health and taste reasons, it’s use in food industry requires that invertase be highly purified
A wide range of microorganisms produce invertase and can, thus, utilize sucrose as a nutrient
How is invertase biosynthesized?
Commercially, invertase os biosynthesized chiefly by yeast strains Saccharomyces cerevisiae or Saccharomyces carlsbergenisis
Even within the sane yeast culture…
Invertase exists in more than one forms
Example, the intracellular invertase has a molecular weight of 135,000 daltons, whereas the extracellular variety has a molecular weight of 270,000 daltons
How is invertase different from other enzymes?
In contrast to most other enzymes, invertase exhibits relatively high activity over a broad range of pH (3.5-5.5), with the optimum near 4.5
What is the max temperature of invertase?
The enzyme activity reaches a maximum at about 55 degrees Celsius
What is the Km value of most enzymes? What is the Km value of invertase?
Most enzymes- between 2Mm and 5Mm
Invertase- 30Mm
How is enzyme activity measured?
[product]/ time
How can we measure inverted activity?
One method used to measure invertase activity utilizes dinitrosalicylic acid (DNS)
DNS is reduced to 3-amino-5-nitrosalicylic acid (ANS)
