Polyamines
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This document discusses polyamines, which are biologically important molecules that possess multiple amino groups. The key polyamines are putrescine, spermine, and spermidine. Spermine and spermidine were originally detected in human semen. Polyamines are synthesized from ornithine and S-adenosyl methionine precursors. Ornithine decarboxylase regulates polyamine synthesis. Polyamines are basic molecules that associate with nucleic acids and are essential for processes like cell growth, proliferation, and membrane stability. Levels of excreted polyamines are elevated in many cancer types, so polyamines can be diagnostic markers for cell proliferation and destruction.
Polyamines
- 1. M.Prasad Naidu MSc Medical Biochemistry, Ph.D,.
- 2. Possess multiple amino groups Putrescine, spermine & spermidine are biologically imp Spermine & spermidine were detected in human semen (sperm) hence the name
- 3. 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. 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. 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. 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