Unusual long polyamines such as caldopentamine and caldohexamine, and branched polyamines such as tetrakis(3-aminopropyl)ammonium andN4 -aminopropylspermidine were often found in cells of extreme thermophiles and hyperthermophiles belonging to both Bacteria and Archaea domains. Some of these unusual polyamines are essential for life at extreme temperatures. In some cases, the unusual polyamines also exist in cells of nonthermophilic organisms and play important physiological roles under normal conditions. Methods for chromatographic analysis, isolation, and chemical syntheses of unusual polyamines as well as experimental methods for measuring their physiological roles are discussed. Especially, many newly improved methods for chemical syntheses are presented in this article.
