RADIATION INACTIVATION ANALYSIS OF MICROSOMAL UDP-GLUCURONOSYLTRANSFERASES CATALYZING MONOGLUCURONIDE AND DIGLUCURONIDE FORMATION OF 3,6-DIHYDROXYBENZO(A)PYRENE AND 3,6-DIHYDROXYCHRYSENE
RADIATION INACTIVATION ANALYSIS OF MICROSOMAL UDP-GLUCURONOSYLTRANSFERASES CATALYZING MONOGLUCURONIDE AND DIGLUCURONIDE FORMATION OF 3,6-DIHYDROXYBENZO(A)PYRENE AND 3,6-DIHYDROXYCHRYSENE
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DOI：
10.1016/0006-2952(94)90198-8
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发表时间：
1994-10-18
影响因子：
5.8
通讯作者：
BOCK, KW
中科院分区：
文献类型：
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作者：
GSCHAIDMEIER, H;BOCK, KW
间接证据表明微粒体UDP-葡萄糖醛酸基转移酶(UGT)的多个亚基参与多环芳烃二酚的二葡萄糖苷酸形成(Beck等人，Mol Pharmacol 42：613-618，1992)。为了证实这一建议，通过辐射灭活分析在微粒体中原位确定了催化这些反应的 UGT 的功能目标尺寸。发现催化 L-萘酚和 6-羟基葡萄糖醛酸化的 UGT 的目标大小分别为 91 +/- 29 和 120 +/- 27 kDa。然而，3,6-二羟基苯并(a)芘形成单葡萄糖苷酸和二葡萄糖苷酸的目标大小分别为118 +/- 33和218 +/- 24 kDa。类似地，使用 3,6-二羟基作为底物，发现 6-O-单葡萄糖醛酸和 3-O-单葡萄糖醛酸形成的目标尺寸为 109 +/- 21 和 101 +/- 23 kDa，而观察到的二葡萄糖醛酸形成的目标尺寸为 192 +/- 34 kDa。基于 UGT 的亚基分子量为 50-60 kDa，这些结果表明参与酚单葡萄糖醛酸苷形成的 UGT 可能以二聚体的形式发挥作用。相比之下，参与多环芳烃二酚的二葡萄糖苷酸形成的UGT可能在微粒体中原位发挥四聚体的作用。
Indirect evidence has suggested that multiple subunits of microsomal UDP-glucuronosyltransferases (UGTs) are involved in diglucuronide formation of diphenols of polycyclic aromatic hydrocarbons (Beck et al., Mol Pharmacol 42: 613-618, 1992). To substantiate this suggestion functional target sizes of UGTs catalysing these reactions were determined in microsomes in situ by radiation inactivation analysis. Target sizes of UGTs catalysing the glucuronidation of l-naphthol and 6-hydroxychrysene were found to be 91 +/- 29 and 120 +/- 27 kDa, respectively. However, target sizes for mono- and diglucuronide formation of 3,6-dihydroxybenzo(a)pyrene were 118 +/- 33 and 218 +/- 24 kDa, respectively. Similarly, using 3,6-dihydroxychrysene as substrate target sizes of 109 +/- 21 and 101 +/- 23 kDa were found for 6-O-monoglucuronide and 3-O-monoglucuronide formation and a target size of 192 +/- 34 kDa observed for diglucuronide formation. Based on subunit molecular masses of 50-60 kDa for UGTs, these results suggest that UGTs involved in monoglucuronide formation of phenols may function as dimers. In contrast, UGTs involved in diglucuronide formation of diphenols of polycyclic aromatic hydrocarbons may function as tetramers in microsomes in situ.