Ronden J E, Soute B A, Thijssen H H, Saupe J, Vermeer C
Department of Biochemistry, University of Limburg, Maastricht, The Netherlands.
Biochim Biophys Acta. 1996 Nov 14;1298(1):87-94. doi: 10.1016/s0167-4838(96)00120-3.
Vitamin K belongs to a class of compounds commonly known as prenylquinones. Three other prenylquinones which are abundantly found in food are plastoquinone-9, ubiquinone-9 and ubiquinone-10. Using in vitro assay systems, it was recently found that synthetic derivatives of prenylquinones inhibit the vitamin K-dependent enzyme gamma-glutamylcarboxylase and, to a lesser extent, the vitamin K-epoxide reductase. In this paper we describe how natural prenylquinones affect the vitamin K-dependent enzymes in vitro. All three prenylquinones were found to inhibit both the vitamin K-dependent carboxylase and the K-epoxide reductase in a rat as well as in a cow liver system; 50% inhibition was obtained at concentrations in the micromolar range. On the basis of their respective standard redox potentials, a possible mechanism for the inhibitory effect of prenylquinones on the carboxylase enzyme is put forward. It is concluded that natural prenylquinones are potential antagonists of vitamin K and may interfere with vitamin K-dependent reactions in vivo.
维生素K属于一类通常被称为异戊二烯醌的化合物。在食物中大量存在的其他三种异戊二烯醌是质体醌-9、泛醌-9和泛醌-10。最近利用体外分析系统发现，异戊二烯醌的合成衍生物可抑制维生素K依赖的γ-谷氨酰羧化酶，在较小程度上还可抑制维生素K环氧化物还原酶。在本文中，我们描述了天然异戊二烯醌在体外如何影响维生素K依赖的酶。在大鼠和牛肝系统中发现，所有这三种异戊二烯醌均可抑制维生素K依赖的羧化酶和K环氧化物还原酶；在微摩尔浓度范围内可达到50%的抑制率。根据它们各自的标准氧化还原电位，提出了异戊二烯醌对羧化酶产生抑制作用的一种可能机制。得出的结论是，天然异戊二烯醌可能是维生素K的潜在拮抗剂，并可能在体内干扰维生素K依赖的反应。
