Oxidation of cis- and trans-acenaphthene-1,2-diol by soluble preparations from rat liver

Abstract

For the past 2 years an on-line computer has been used for hospital biochemistry. Currently the system covers 80% of the work load of the laboratory (250000tests/annum).Standard AutoAnalyzers are used as basic analytical instruments and these are coupled to a PDP 8/S computer. The system collects data simultaneously from 12 test channels fed from six sample channels. Input of command instructions, the collection and processing of data and the output of results occur as time-shared processes. Results are identified by specimen laboratory accession number entered into the system manually. Each test channel is calibrated in terms of a third-order polynomial expressing the assay value as a function of the peak readings. Correction is applied for calibration drift and specimen interaction. Factors that were considered in the design ofthe system and the main features of the program are presented and discussed. COMMUNICATIONSOxidation of cis-and trans-Acenaphthene- 1,2-diol by Soluble Preparations from RatLiver By ELIZABETH C. DRUMMOND, P. CALLAGHAN andThe dehydrogenation of ci8-and tran8-acenaphthene-1,2-diol to acenaphthenequinone by a rat liver microsomal preparation was demonstrated by Drummond & Hopkins (1969). Ayengar, Hayaishi, Nakajima & Tomida (1959) partially purified an enzyme (catechol reductase, EC 1.3.1.5) from acetone-dried rabbit liver powder that dehydrogenates tranm-1,2-dihydrobenzene-1,2-diol to 1,2-dihydroxybenzene in the presence of NADP+, and a similar reaction would be involved in the oxidation of the acenaphthenediols to acenaphthenequinone if 1,2-dihydroxyacenaphthylene were the initial dehydrogenation product.In the present work a preparation was obtained from acetone-dried rat liver powder that dehydrogenates trans-acenaphthene-1,2-diol in the presence of NADP+. The preparation was assayed by following the increase in extinction at 340nm due to the diol oxidation product and NADPH in 50mM-tris-HCl, pH9.0, at 37°C. The preparation was made by chromatographing the 100 0OOg supernatant of a suspension of the acetone-dried powder in 0.15M-potassium chloride on Sephadex G-25 equilibrated with lOmM-tris-HCl, pH8.0. This removes endogenous cofactor-reducing activity. The protein eluate was further chromatographed on DEAE-cellulose equilibrated in the same buffer, the column being eluted with a sodium chloride gradient. A fraction was obtained with nine times the specific activity of the Sephadex G-25 eluate. This preparation differed from the microsomal system in that it catalysed the oxidation of trans-acenaphthene-1,2-diol more readily than that of the 08-isomer, and required NADP+, and not NAD+, as cofactor. A preparation with these properties was also obtained from the 1000OOg supernatant of a homogenate of rat liver. An almost identical protein elution profile was obtained from the DEAE-cellulose column, and a similar degree of purification was achieved.After incubation of tran8-acenaphthene-1,2-diol and NADP+ at 370C with a preparation of the soluble enzyme at pH 9.0 for 2h, acenaphthenequinon...

Investigation of the metabolic oxidation of acenaphthen-1-ol

“…Following the suggestion of Hopkins (1968) that oxidation of the acenaphthene-1,2-diols to 1,8-naphthalic acid might involve an initial dehydrogenation step, acenaphthenequinone was isolated from a microsomal incubation of the acenaphthene-1,2-diols in the presence of NAD+ (Drummond & Hopkins, 1969). Drummond, Callaghan & Hopkins (1971) have demonstrated that there are at least two systems in rat liver that dehydrogenate acenaphthene-1,2-diol, one in the microsomal fraction and another in the soluble fraction. These findings and the work of Sims (1966), on the structurally related 3-methylcholanthrene, led us to investigate the metabolism of acenaphthen-l-ol in order to determine whether it proceeds by a pathway involving an initial dehydrogenation reaction.…”