Periplasmic space

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The periplasmic space is the space seen between the plasma membrane and the outer membrane in the Gram-negative bacteria. The substance that occupies the periplasmic space is referred to as periplasm. A very small periplasmic space between the plasma membrane and the peptidoglycan layer (cell wall) may be observed in the Gram-positive bacteria.[1] The periplasmic space is a lot thicker in Gram negative bacteria. Periplasmic space may be filled with a loose network of peptidoglycan and may constitute up to 40% of the total cell volume.[2] This space is involved in various biochemical pathways including nutrient acquisition, synthesis of peptidoglycan, electron transport, and alteration of substances toxic to the cell.[3] Gram-positive bacteria do not have as many periplasmic proteins compared to the Gram-negative bacteria.[3] Instead Gram-positive bacteria secrete enzymes which would normally be found in the periplasmic space of the Gram-negative bacteria. This secreted enzyme is referred to as an exoenzyme.[3]

The periplasmic space is of particular clinical importance in that it is the site, in some species, that contains beta-lactamase, an enzyme responsible for degrading the penicillin group of antibiotic drugs, leading to penicillin resistance.

[edit] References

  1. ^ Zuber B, Haenni M, Ribeiro T, et al (2006). "Granular layer in the periplasmic space of gram-positive bacteria and fine structures of Enterococcus gallinarum and Streptococcus gordonii septa revealed by cryo-electron microscopy of vitreous sections". J. Bacteriol. 188 (18): 6652–60. doi:10.1128/JB.00391-06. PMID 16952957. 
  2. ^ Otto Holst; Guntram Seltmann. The Bacterial Cell Wall. Berlin: Springer. ISBN 3-540-42608-6. 
  3. ^ a b c Klein, Donald W.; Prescott, Lansing M.; Harley, John (2005). Microbiology. Boston: McGraw-Hill Higher Education. ISBN 0-07-295175-3. 
  • D. White, The Physiology and Biochemistry of Prokaryotes, Oxford University Press, Oxford, 2000, pp. 22.
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