The dehydrochlorination of 1 , 1 , I-trichloro-2,2-bis(p-chlorophenyl)ethane to its nontoxic, ethylenic analogue, DDE,* by extracts of DDT-resistant houseflies (1Musca domestica) was first demonstrated by Sternburg et al. (I). It was shown that this system was GSH-dependent and that no DDT dehydrochlorinase could be detected in DDT-susceptible flies by the means then available. The titer of DDT...

The appropriate conditions for determining angiotensin-converting enzyme in human serum with use of 2-furanacryloyl-L-phenylalanylglycylglycine as substrate are described. The method, a modification of that reported by Holmquist et al. (Anal. Biochem. 95:540-548, 1979) for purified rabbit lung enzyme, is based on the blue shift of the absorption spectrum that occurs upon hydrolysis of the subst...

The rate of phosphoenolpyruvate carboxylase activity measured through the conventional coupled assay with malate dehydrogenase is underestimated due to the instability of oxaloacetate, which undergoes partial decarboxylation into pyruvate in the presence of metal ions. The addition of lactate dehydrogenase to the conventional assay allows the reduction of pyruvate formed from oxaloacetate to la...

Direct and reliable spectrophotometric method for assaying total carotenes (TC) in margarines with the minimum of sample manipulation is proposed. For the first time saponification step used in determination of carotenes in margarines was omitted leading to a substantial cost saving and reduction of time needed to complete the analysis. The resulting analytical procedure is characterized in det...

other Rhizobium species. Most of these plasmids encoding for fixation and nodulation properties are non-self transmissible. Plasmid profiles were determined for 24 strains of R. trifolii. All the strains harboured at least three plasmids and as many as eight were present in some strains. Southern hybridization with cloned R. meliloti nifgenes was used to identify indigenous Nif plasmids. Each s...

The aim of this work was to discover the extent of interference by phosphoenolpyruvate (PEP) phosphatase in spectrophotometric assays of PEP carboxylase (EC 4.1.1.31) in crude extracts of plant organs. The presence of PEP phosphatase and lactate dehydrogenase (EC 1.1.1.27) in extracts leads to PEP-dependent NADH oxidation that is independent of PEP carboxylase activity, and hence to overestimat...

A very simple, accurate, rapid and economical UV spectrophotometric method was developed for the estimation of fluconazole. The UV method permits a simple, rapid and economical quantitation of fluconazole in capsule dosage form only. The maximum absorbance of fluconazole was found to be 210 nm. Fluconazole, which is available in Karachi in different brands within the pharmacies, was collected a...

An inverse relationship between the concentration of ribose 5-phosphate and apparent ribulose bisphosphate carboxylase activity was observed. The Lilley-Walker assay spectrophotometric assay, in which the 3-phosphoglyceric acid-dependent oxidation of reduced pyridine nucleotide is measured, is shown to be highly sensitive to inhibition by heavy metals. Analysis of the purity of reagents showed ...