Gostatin is an inhibitor of aspartate aminotransferase (GOT). It can be found in *Streptomyces sumanensis* nov. sp. NK-23. Gostatin strongly inhibits pig heart GOT but exhibits weaker inhibition on wheat germ GOT and GPT, with no significant effect on glutamate dehydrogenase and glutamine synthetase. Its inhibition mechanism resembles substrate-competitive inhibition, with aspartate providing a protective effect against its inhibitory action. Gostatin is useful for studying the catalytic mechanism of GOT and its role in nitrogen metabolism.