Gahl W A, Pitot H C
In Vitro. 1979 Apr;15(4):252-7. doi: 10.1007/BF02618948.
Putrescine-oxidase activity was found in fetal bovine serum (FBS) with a pH optimum of 8.0 and in adult bovine serum (ABS) with a pH optimum of 9.8. The crude FBS enzyme had a KM for putrescine of 2.58 x 10(-6) M and a Vmax of 0.53 nmol per hr per 50 microliter serum. Aminoguanidine competitively inhibited the enzyme with a KI of 1.8 x 10(-8) M. Spermidine and spermine proved competitive inhibitors of putrescine for both the FBS and the crude ABS putrescine oxidases. The Vmax for the ABS putrescine oxidase was 2.10 nmol per hr per 50 microliter serum, and the KM for putrescine, 50.3 x 10(-6) M. The K1 of the ABS putrescine oxidase for aminoguanidine was 41 x 10(-6) M. On the basis of both the KM and KI values, the adult serum enzyme, at its optimal pH of 9.8, bound spermidine and spermine more avidly than the smaller putrescine and aminoguanidine; whereas the FBS enzyme, at pH 8.0, bound aminoguanidine and putrescine more tightly than the larger polyamines. Each of the enzymes retained over 80% of its activity after heating at 56 degrees C for 30 min. Applications of these data to the study of polyamines in tissue culture and to the purification of diamine oxidases are discussed.
在胎牛血清（FBS）中发现了腐胺氧化酶活性，其最适pH为8.0，在成年牛血清（ABS）中也发现了该酶活性，最适pH为9.8。FBS粗酶对腐胺的米氏常数（KM）为2.58×10⁻⁶ M，最大反应速度（Vmax）为每50微升血清每小时0.53纳摩尔。氨基胍对该酶有竞争性抑制作用，抑制常数（KI）为1.8×10⁻⁸ M。亚精胺和精胺对FBS和ABS粗腐胺氧化酶来说都是腐胺的竞争性抑制剂。ABS腐胺氧化酶的Vmax为每50微升血清每小时2.10纳摩尔，腐胺的KM为50.3×10⁻⁶ M。ABS腐胺氧化酶对氨基胍的KI为41×10⁻⁶ M。基于KM和KI值，成年血清酶在其最适pH 9.8时，比小分子的腐胺和氨基胍更 avidly地结合亚精胺和精胺；而FBS酶在pH 8.0时，比大分子的多胺更紧密地结合氨基胍和腐胺。在56℃加热30分钟后，每种酶都保留了超过80%的活性。讨论了这些数据在组织培养中多胺研究以及二胺氧化酶纯化中的应用。 （注：avidly这个词在文中不太明确准确意思，推测可能是“强烈地”之类意思，这里保留原文未准确翻译）
