ABSTRACT
Polyamines are biologically active low molecular weight diamines and triamines which include putrescine, spermidine and spermine. These are regarded as essential for cell multiplication differentiation, and as co-factors for the synthesis of macromolecules (Marton and Morris, 1987; Pegg and McCann, 1988). They can also contribute to the stabilization of membranes at higher temperature (Tabor and Tabor, 1984). Other diamines such as cadaverine, triamines such as norspermine and norspermidine, tetramines and pentamines are also functional in some microorganisms (Table 42.1) (Villanueva, 1981). In mammalian cells and the majority of protozoa, synthesis of polyamines occurs by the decarboxylation of ornithine to putrescine by ornithine decarboxylase (ODC) (Linstead and Cranshaw, 1983; Pegg and McCann, 1988; Yarlett, 1988) (Figure 42.1). In plants, fungi, many prokaryotes and possibly Trypanosoma cruzi (Pegg and McCann, 1988), agmatine, which is derived from the decarboxylation of arginine, is the precursor of putrescine.
