Polyamines.ppt

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POLYAMINES

• M.Prasad Naidu
• MSc Medical Biochemistry, Ph.D,.

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polyamines

• Possess multiple amino groups
• Putrescine, spermine spermidine are
  biologically imp
• Spermine spermidine were detected in human
  semen (sperm) hence the name

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Biosynthesis

• Precursors Ornithine SAM ( only the four
  carbon moiety but not CH3)
• Ornithine decarboxylase splits off CO2 and
  produce Putrescine
• Ornithine decarboxylase has the shortest half
  life ( 10 min) among the mammalian enzymes
• It regulates polyamine synthesis
• Activators corticosteroids, testosterone, GH

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Degradation of polyamines

• Polyamine oxidase of liver peroxisomes oxidizes
  spermine to spermidine and then to putrescine
• Spemidine and putrescine are excreted in urine in
  a conjugated form, as acetylated derivatives
• Some amount of putrescine is also oxidized to NH3
  and CO2

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Functions

• Basic in nature
• Possess multiple positive charges
• Hence they are readily associated with nucleic
  acids
• Synthesis of DNA RNA and proteins

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• Essential for cell growth proliferation
• Some enzymes are inhibited by polyamines (
  protein kinase)
• Stabilization of membrane structure (cell and
  cellular organelles)

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Clinical importance

• The excretion of Polyamines is found to be
  elevated in almost all types of cancers
• Eg leukemias carcinoma of lungs, bladder,
  kidney
• Diagnostically putrescine is an ideal marker for
  cell proliferation
• Spermidine is suitable for the assessment of cell
  destruction

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Thank you