The properties of tubulins from Brugia malayi, B. pahangi, Nippostrongylus brasiliensis and rat brain were compared. Tubulins from all nematodes and rat brain were partially purified by polylysine agarose chromatography, those of brain also by cycles of assembly/disassembly, and all by taxol-induced assembly. The tubulins were compared with respect to concentration ($ mu$g tubulin/mg soluble protein), drugs binding and isoforms. The tubulins of B. malayi and B. pahangi were similar. However, the tubulin from these filariae were different from those of N. brasiliensis. Even larger differences were detected between the nematode tubulins and those of rat brain. However, all tubulins reacted to $ alpha$- and $ beta$-tubulin monoclonal antibodies, and had similar mobility on SDS-PAGE. Different peptide maps were obtained for N. brasiliensis tubulin compared with rat brain tubulin. Tubulins of N. brasiliensis bound more mebendazole than did those of Brugia nematodes (B$ sb{ rm max}$: pmoles/$ mu$g tubulin). The binding of benzimidazoles to nematode tubulins was much higher than to rat brain tubulin. Benzimidazole binding to brain tubulin was influenced by the degree of assembly of the tubulin. This did not appear to be the case for the nematode tubulins. In vitro translation of B. malayi mRNA resulted in two isoforms for both $ alpha$- and $ beta$-tubulins in contrast to the 4 $ alpha$- and 4-5 $ beta$-isoforms found naturally. This suggest post translational modification of tubulin may take place in B. malayi. This study has characterized some of the differences that exist between mammalian tubulins and those of nematodes on the one hand, and between the tubulins of a gastrointestinal nematode (N. brasiliensis) and those of filariae (B. malayi and B. pahangi) on the other hand.

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