LAB 2 Flashcards
Protein Isolation
One method to isolate a particular protein from a mixture of soluble substances is through
Protein Precipitation
Two commonly used techniques of protein precipitation:
salting-out method
isoelectric precipitation
In the salting-out process, proteins are
usually precipitated out of the solution by
saturating the protein solution with
Ammonium sulfare or magnesium sulfate
By ______ the ionic strength of the
solution, the solubility of the protein _____, thereby causing the protein to precipitate out of the solution
Increasing, decreasing
How does increasing the ionic strength of a solution affect protein solubility?
Increasing ionic strength decreases protein solubility, leading to precipitation.
Why does protein precipitation occur when ionic strength increases?
Water molecules preferentially interact with salt ions, reducing protein-water interactions and promoting protein aggregation.
What happens to protein molecules when they lose their interaction with water?
They aggregate and precipitate out of the solution.
Why do different proteins have different solubility levels at specific salt concentrations?
Each protein has a unique structure and charge distribution, affecting its interaction with water and salt ions.
How can salt concentration be used to isolate a particular protein?
By carefully adjusting salt concentration, specific proteins can be selectively precipitated while others remain in solution
How does pH affect the solubility of proteins?
pH alters the ionization state of protein functional groups, affecting their net charge and solubility.
What happens to a protein at its isoelectric point (IpH)?
The protein has a net charge of zero, making it least soluble and more likely to precipitate.
Why are proteins more soluble at pH levels above or below their isoelectric point?
At pH values other than the IpH, proteins carry a net charge, leading to electrostatic repulsion and increased solubility.
What is the principle behind isoelectric precipitation?
By adjusting the pH of a solution to match a protein’s isoelectric point, the protein loses its charge and precipitates
Why can proteins no longer interact with other solution components at their isoelectric point?
With a net charge of zero, proteins cannot effectively interact with water molecules or other charged particles, leading to precipitation.
a protein found in egg whites
Ovalbumin
Ovalbumin will be precipitated using
Ammonium sulfate precipitation
Constitute the majority of a biological system
Proteins
Casein is precipitated using
Isoelectric precipitation
Very common procedure in biochemistry
Protein Isolation
Why isolate proteins
To gain insights
For use in Medicine
For use in Industry
Why are proteins considered labile?
Proteins are large and delicate, and their shape can easily change (denature), leading to a loss of biological activity.
How does protein denaturation affect its function?
Denaturation alters the protein’s shape, causing a loss of its biological activity.
Why must mild procedures be used in protein isolation techniques?
Harsh conditions can denature proteins, so gentle methods are needed to maintain their structure and function.
What makes proteins similar to one another?
All proteins are composed of the same amino acids, differing only in their proportions, sequences, and 3D folding.
