Hext P M, Rose F A
Biochem J. 1975 Aug;150(2):175-81. doi: 10.1042/bj1500175.
Cytosol preparations of rat liver and kidney were examined for their ability to transfer sulphate from adenosine 3'-phosphate 5'-sulphatophosphate to p-hydroxyphenylpyruvic acid. Little activity towards this substrate was observed, and the main product detected in the reaction mixtures was identified as p-hydroxybenzyl alcohol O-sulphate. This was not formed from p-hydroxybenzaldehyde, a spontaneous oxidation product of p-hydroxyphenylpyruvic acid, by sulphation followed by a rapid enzyme-catalysed reduction of the intermediate phydroxybenzaldehyde O-sulphate. This product was formed mainly by this sequence of reactions, but the reverse, reduction followed by sulphation, also appeared possible. p-Hydroxybenzyl alcohol itself was very readily sulphated by both preparations, and the liver also produced a sulpho-conjugate of homogentisic acid. These observations are important in calculating the turnover of L-tyrosine O-sulphate in the mammalian system, and establish that p-hydroxyphenylpyruvic acid O-sulphate is an end product of its metabolism, rather than an intermediate in its synthesis by reversed transamination.
对大鼠肝脏和肾脏的胞质溶胶制剂进行了检测，以考察它们将硫酸根从3'-磷酸腺苷5'-磷酸硫酸转移至对羟基苯丙酮酸的能力。观察到对该底物的活性很低，并且在反应混合物中检测到的主要产物被鉴定为对羟基苄醇O-硫酸盐。它不是由对羟基苯丙酮酸的自发氧化产物对羟基苯甲醛通过硫酸化作用，随后中间产物对羟基苯甲醛O-硫酸盐经快速酶催化还原而形成的。该产物主要通过这一系列反应形成，但反过来，先还原后硫酸化似乎也是可能的。两种制剂都能很容易地将对羟基苄醇自身硫酸化，并且肝脏还产生了尿黑酸的硫酸结合物。这些观察结果对于计算哺乳动物系统中L-酪氨酸O-硫酸盐的周转率很重要，并确定对羟基苯丙酮酸O-硫酸盐是其代谢的终产物，而不是通过逆向转氨作用合成它的中间体。
