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Spermine is a polyamine involved in cellular metabolism that is found in all eukaryotic cells. The precursor for synthesis of spermine is the amino acid ornithine . It is an essential growth factor in some bacteria as well.
Spermine is synthesized from the reaction of spermidine with SAM in the presence of the enzyme spermine synthase. The polyamines undergo rapid interconversion in the polyamine cycle, in which putrescine leads to synthesis of spermidine and spermine, with degradation of these polyamines to form putrescine, which can begin the cycle again. [16]
Spermidine/spermine N(1)-acetyltransferase (SPD/SPM acetyltransferase) is a rate-limiting enzyme in the catabolic pathway of polyamine metabolism. It catalyzes the N(1)-acetylation of spermidine and spermine and, by the successive activity of polyamine oxidase , spermine can be converted to spermidine and spermidine to putrescine . [ 7 ]
Putrescine, a kind of polyamine, decreaseS phytochelatin synthesis at enzymatic and gene expression levels by increasing cadmium toxicity in rice. Polyamines provide protection against heavy metals such as inhibiting Cadmium uptake or its entry into the cells because exogenous polyamines are mainly allocated to the apoplast.
Spermidine is an aliphatic polyamine. Spermidine synthase (SPDS) catalyzes its formation from putrescine. It is a precursor to other polyamines, such as spermine and its structural isomer thermospermine.
Spermine synthase is an enzyme involved in polyamine biosynthesis. It is present in all eukaryotes and plays a role in a variety of biological functions in plants [ 3 ] Its structure consists of two identical monomers of 41 kDa with three domains each, creating a homodimer formed via dimerization .
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Spermine synthase in turn helps the body produce spermine, a polyamine critical to cell processes such as cell division, tissue repair, and apoptosis. [5] The resulting shortage of spermine in cells causes problems with development and brain function, though the exact mechanism is not understood.