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What is periplasmic extraction?

What is periplasmic extraction?

The process extracts periplasm using cold osmotic shock with magnesium, prior to sonication and ultracentrifugation to separate the cytoplasm from insoluble material. This method handles cells cultivated in various conditions and allows preparation of active proteins in their respective compartments.

What is in the periplasm of E coli?

The E. coli periplasm contains over 60 known proteins, including binding proteins for amino acids, sugars, vitamins, and ions; degradative enzymes (phosphatases, proteases, and endonucleases); and antibiotic detoxifying enzymes (β-lactamases, alkyl sulfodehydrases, and aminoglycoside phosphorylating enzymes).

What is the principle used in osmotic shock?

Osmotic shock is the technique of weakening cells caused by lysis, which is brought about by increased internal pressure as water rapidly enters cells when cells are subjected to high osmotic pressure followed by sudden dilution (Middelberg, 1995).

How do you do osmotic shock?


  1. Grow bacteria overnight in 100 ml of the appropriate medium.
  2. Harvest the bacteria by spinning at 10,000 X g (7,000 rpm in SS34 Sorvall rotor), 4ºC for 10 minutes.
  3. Resuspend the pellet with 8 ml of 0.05 M Tris-HCl pH 7.3, 0.2 M MgCl.
  4. Chill in water-ice bath for 15 minutes.
  5. Warm at 30ºC.
  6. Repeat step 4.

Do gram negative bacteria have Periplasm?

Gram-negative bacteria are surrounded by two membrane bilayers separated by a space termed the periplasm. The periplasm is a multipurpose compartment separate from the cytoplasm whose distinct reducing environment allows more efficient and diverse mechanisms of protein oxidation, folding, and quality control.

What is the role of sucrose in solubilization buffer?

To break or lysis the cell wall including the wall of the nucleus we have to create the osmotic pressure so that the wall bursts and cell contents release by the action of proteolytic enzymes along with sucrose that present in the extraction buffers. Hope it is clear why we add sucrose in buffers.

Do gram negative bacteria have periplasmic space?

Is E. coli Gram positive or negative?

Escherichia coli (E. coli) is a Gram-negative, rod-shaped, facultative anaerobic bacterium. This microorganism was first described by Theodor Escherich in 1885.

How do cells respond to osmotic shock?

The initial cellular response to osmotic stress is the production of osmolytes (e.g., sorbitol and betaine) that stabilize molecular structures and prevent protein misfolding. Prolonged osmotic stress results in delayed cell cycle, DNA damage and apoptosis [98].

What is the osmotic effect due to?

Osmotic and oncotic pressure Osmotic pressure is the pressure caused by water at different concentrations due to the dilution of water by dissolved molecules (solute), notably salts and nutrients.

What type of stress is called osmotic stress?

Osmotic shock or osmotic stress is a sudden change in the solute concentration around a cell, causing a rapid change in the movement of water across its cell membrane. Under conditions of high concentrations of either salts, substrates or any solute in the supernatant, water is drawn out of the cells through osmosis. (

What is difference between Gram positive and Gram-negative bacteria?

Gram positive bacteria have a thick peptidoglycan layer and no outer lipid membrane whilst Gram negative bacteria have a thin peptidoglycan layer and have an outer lipid membrane.

How to make a modified osmotic shock for periplasmic release?

In the standard osmotic shock, the cell pellet was resuspended in a solution (8 mL, 4 °C) containing 20% (w/v) sucrose, 33 mM Tris–HCl (pH 8.0), and 0.5 mM Na 2 EDTA. After a shaking incubation for 10 min, the shrunk cells were harvested by centrifugation at 8000× g for 10 min.

How is osmotic shock used to recover E coli?

Osmotic shock is a popular method for recovery of recombinant proteins from the periplasmic space of E. coli. This method depends on the increase in the permeability of the outer membrane, which is achieved through the release of LPS by EDTA treatment.

What is the maximum yield of an osmotic shock?

It can be seen that, in the standard osmotic shock (0 mM Ca 2+ ), the creatinase yield reached its maximum (1300 U/g cell) at 0.5 mM EDTA, and in all cases the periplasmic release was insignificant in the absence of EDTA.

How is aqueous solution used in osmotic shock?

Use of aqueous solution with varying ionic strengths enables the selective extraction of proteins by utilizing the salting-in and/or salting-out phenomenon of food proteins ( Boye and Barbana, 2012 ).