Moore G P, Sullivan D T
Biochim Biophys Acta. 1975 Aug 26;397(2):468-77. doi: 10.1016/0005-2744(75)90137-0.
Two enzymic forms of kynurenine formamidase (EC 3.5.1.9) from Drosophila melanogaster were separated and partially purified by pH fractionation, (NH4) 2SO4 fractionation and Sephadex G-75 gel filtration. The enzymes were also separated by DEAE-cellulose ion-exchange chromatography and distinguished by their different rates of thermal inactivation. The multiple forms are termed formamidase I and formamidase II. The molecular weight of formamidase I as measured by Sephadex G-75 chromatography is 60 000 and that of formamidase II is 31 000. The pH optima are broad, ranging between 6.7 and 7.8 for formamidase I and 6.5 and 8.0 for formamidase II. The apparent Km values are 5-10(-3) and 0.83-10(-3) M, resepctively. The possibility that formamidase II is an active subunit of formamidase I is discussed, although neither enzyme will convert to the other when separated and rechromatographed. Eight organisms were tested for the presence or absence of multiple forms of formamidase. Drosophila melanogaster and Drosophila virilis have both enzymes; cow, chicken, yeast and housefly have formamidase I only, and mouse and frog have formamidase II only.
通过pH分级分离、硫酸铵分级分离和葡聚糖凝胶G-75凝胶过滤，对黑腹果蝇中的犬尿氨酸甲酰胺酶（EC 3.5.1.9）的两种酶形式进行了分离和部分纯化。这些酶还通过DEAE-纤维素离子交换色谱法进行了分离，并根据它们不同的热失活速率进行了区分。这些多种形式被称为甲酰胺酶I和甲酰胺酶II。通过葡聚糖凝胶G-75色谱法测得甲酰胺酶I的分子量为60000，甲酰胺酶II的分子量为31000。甲酰胺酶I的最适pH范围较宽，在6.7至7.8之间，甲酰胺酶II的最适pH在6.5至8.0之间。表观Km值分别为5×10⁻³和0.83×10⁻³ M。尽管将两种酶分离并重新色谱分析时，它们都不会相互转化，但仍讨论了甲酰胺酶II是甲酰胺酶I的活性亚基的可能性。对8种生物进行了测试，以确定是否存在多种形式的甲酰胺酶。黑腹果蝇和粗壮果蝇都有这两种酶；牛、鸡、酵母和家蝇只有甲酰胺酶I，而小鼠和青蛙只有甲酰胺酶II。
