Quiz Block 2 Flashcards
Mention an agent that is commonly used for precipitation of succinct acid?
Calcium hydroxide (CaOH)
Ammonium sulphate (NH4SO4)
True or False: In the context of precipitation, the flocculation step is enhanced when electrostatic repulsion is minimised?
True - If repulsion is minimized, the particles aggregate
Can you give one example of a compound that is used in the process of “salting out” in protein precipitation
Ammonium sulphate (NH4SO4) is the most common
It is also possible to use phosphate salts
Liquid-liquid extraction processes are normally more efficient when the extractors are set in concurrent/countercurrent fashion. Aqueous two-phase extraction systems are/are not particularly recommended for protein extraction
Countercurrent - Allows for higher driving force
Are recommended for protein extraction
What is the driving force in electrodialysis?
Electric potential difference
Separate the terms dealing with electrodialysis vs liquid-liquid extraction: Water splitting – Partition coefficient – Bipolarity – Two phase extraction – Agitated columns – Catode
Electrodialysis: Bipolarity, Catode, Water splitting
Liquid-liquid extraction: Partition coefficient, two-phase extraction, agitated extraction columns
Why is chromatography not recommended for purification of succinct acid
Selectivity is limited and the yield is low
Chromatography is very expensive
Which cells are generally considered the easiest to disrupt?
Mammalian cells are easier to disrupt
Plant cells are harder to disrupt due to rigid and strong cell wall
What is often a big issue after cell disruption that has to be solved by dilution?
High viscosity
What gives the cell wall of Gram-positive bacteria its mechanical support?
Compound cell wall made of peptidoglycan
What physiological property of Gram-negative bacterial cell walls has to ve considered when planning their disruption?
The cell wall has an outer lipopolysaccharide membrane
Over-expression of recombinant protein products in bacteria often leads to the formation of x
Inclusion bodies
Which enzyme can be used to break down bacterial cell walls?
Lysozyme
What causes cells to break during high pressure homogenization?
Shear stress
- Using a high pressure homogenizer you obtain 53% release of protein in one pass, when disrupting E.coli. How many passes do you need to ensure 90% release? Use ln(Rm/(Rm-R)=K*N
No. of passes 1
Protein release (R) = 0.53 (68%)
Required release = 0.90 (90%)
Substitite the date into the equation:
ln(1/(1-0.53)=K*1, solve for K
K=0.755
Substitute K into the equation with the required release:
ln(Rm/(Rm-R)=KN
ln(1/(1-0.90))=0.755*N, solve for N
N = 3.049
