前文曾報道橘黴素能抑制動物組織和細菌的細胞呼吸。這些結果易使人猜想到此種抗生素可能作用於細胞中存在的酶或酶系。事實上已有人實驗證明橘黴素能抑制金色葡萄球菌的乳酸脫氫酶和微生物的異咯嗪色素酶(flavine enzymes)。現在存在的問題是:橘黴素是否對於其他的酶類,特別是其他呼吸酶類也有顯著作用?是否對於酶都有毒性 Citric acid was reported previously to inhibit cellular respiration in animal tissues and bacteria. These results make it easy to guess that such antibiotics may act on enzymes or enzymes present in the cells. In fact, it has been experimentally demonstrated that citrinin can inhibit S. aureus lactate dehydrogenase and microorganisms of the flavoring enzymes. The question now is whether citrulline has a significant effect on other enzymes, especially other respiratory enzymes, and whether they are toxic to enzymes