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POLYAMINES

BIOCHEMISTRY

mprasadnaidu
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POLYAMINES

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  1. POLYAMINES M.Prasad Naidu MSc Medical Biochemistry, Ph.D,.

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

  3. 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

  4. 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

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

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

  7. 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

  8. Thank you

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