Genetic engineering of beta-galactosidase (EC 3.2.1.23) has led to the development of a new homogeneous assay system, CEDIA. The Z gene of the lac operon of Escherichia coli encodes a large enzymatically inactive polypeptide that spontaneously aggregates and folds to form active beta-galactosidase. Using recombinant DNA techniques, we have been able to engineer beta-galactosidase protein into a large polypeptide (an enzyme acceptor, EA) and a small polypeptide (an enzyme donor, ED). The EAs and EDs are both enzymatically inactive, but spontaneously associate to form enzymatically active tetramers. In the assay, hapten or analyte is attached to an ED, and an analyte-specific antibody is used to inhibit the spontaneous assembly of active enzyme. Analyte in a patient's serum competes with the analyte in the analyte-ED conjugate for antibody, modulating the amount of beta-galactosidase formed. The signal generated by enzyme substrates is directly proportional to the analyte concentrations in the patient's serum. We describe quick (5-15 min) colorimetric tests for digoxin, requiring no serum pretreatments or predilutions and suitable for use with centrifugal and random-access analyzers.
Nitrosodiethanolamine is found in synthetic cutting oils and in many cosmetic preparations and is probably the N-nitroso compound to which human exposure is greatest. It is formed by reaction of the commonly used amines diethanolamine and triethanolamine with nitrosating agents. An assessment of the possible risk in human exposure to nitrosodiethanolamine must be based on sound chronic toxicity data. A previously published chronic test of this compound in rats has shown it to induce liver tumours after very high oral doses, and tumours of the nasal cavity after administration of high repeated doses to Syrian hamsters by subcutaneous injection. To improve our understanding of the carcinogenic potency of nitrosodiethanolamine, we undertook a more extensive study, in which the compound was administered at concentrations ranging from 3,900 to 31,250 parts per million (p.p.m.) in drinking water, to groups of rats for about 6 months. We report here that when the animals were killed, all bore hepatocellular carcinomas, many of which metastasized at the higher doses, indicating that nitrosodiethanolamine is a carcinogen of considerable potency in the rat. However, it is inactive or very weakly active in short-term tests, such as the Salmonella mutagenesis test developed by Ames.
Synthesis of Substituted Benz(a]anthracene-7,12-diones Calcd for C16H1204, parent ion mle 268.073; found 268.071.Preparation of V. Into a pressure bottle was placed 0.09 g (0.43 mmol of III,25 mL of benzene, and a Teflon stirring bar. The solution was cooled to -78 "C and excess I was condensed in. The bottle was capped and the reaction flask was heated to 90 "C and stirred overnight. The flask was then cooled and vented and the solvent was removed under reduced pressure. The crude product was dissolved in 5 mL of hexane and poured into a column of alumina. Elution with hexane removed butadiene polymer. This wm followed by elution with 15% EtOAc/hexane to move the desired product from the column. The eluent was evaporated to yield 0.10 g (90%) of V (greenish crystals), whose spectral (UV, NMR) properties were identical with those of an authentic sample (Aldrich), mp 165-166 "C (lit. mp 166-167 "C).4 2-Methoxy-V was prepared as above by the reaction of 0.10 g (0.42 mmol) of 6-methoxy-111 and excess 9.7 g (200 mmol) of I to yield 0.11 g (91%) of V (yellow crystals), mp 195 "C (lit. mp 200 0C):28 NMR 6 9.2 (d, 1 H, J = 4 Hz), 8.3-8.0 (m, 4 H), 7.8-7.65 (m, 3 H), 7.3 (d, 1 H, J = 4 Hz), 4.0 (s, 3 H); IR, C=O 1670 cm-', C=C 1625; UV 2236 %, (e 1.93 X lo"), 2555 (1.71 X lo"), 2903 (9.5 X lo3), 3010 (8.25 X lo3), 44083-Methoxy-V was prepared as above by the reaction of 0.05 g (0.21 mmol) of 7-methoxy-I11 and excess 9.7 g (200 mmol) of I to yield 0.045 g (75%) of 3-methoxy-V (yellow crystals), mp 145 "C: NMR 6 9.5 (d, 1 H, J = 10 Hz), 8.3-7.9 (m, 4 h), 7.75-7.6 (m, 2 H), 7.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.