A strain of Escherichia coli was isolated in which dihydrofolate reductase was not detected by an enzyme assay or by competition for antibody. This strain requires methionine, glycine, a purine, and thymidine for growth in addition to the auxotrophic requirements of the parent strain. It was found to be useful as a recipient of plasmids harboring dihydrofolate reductase genes.

Polyamine induced aggregation of various DNAs has been studied under conditions usually employed in many enzymatic assays where DNA is one of the substrates. Spermine was by far the most efficient polyamine in causing aggregation followed by spermidine and cadaverine. All double-stranded and naturally occurring single-stranded DNAs were found to aggregate. No aggregation of single-stranded homo...

A rapid and accurate enzymatic assay has been developed for the determination of blood serum levels of BB-K8 and other suitable aminoglycoside antibiotics.

This review summarizes our knowledge of analogs and derivatives of diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A), the most extensively studied member of the dinucleoside 5',5"'-P1,Pn-polyphosphate (NpnN) family. After a short discussion of enzymes that may be responsible for the accumulation and degradation of Np4)N's in the cell, this review focuses on chemically and/or enzymatically produced...

results the results showed that sensitivity and specificity were respectively 84.12% and 92% for‎ recombinant protein srs3 and 92% and 96% for rsag1. conclusions recombinant proteins srs3 and rsag1 are promising antigens in diagnostic assays for detection of specific antibodies against t. gondii. background infections by the protozoan parasite toxoplasma gondii (t. gondii) are widely prevalent ...

The occurrence of increased serum enzyme activity in patients with diseases involving tissue damage such as myocardial infarcation suggested that placental damage may also give rise to characteristic changes in maternal serum enzymes, which might be useful diagnostically. One of the problems in obstetrics is the recognition of placental 'dysfunction' or 'insufficiency', terms which are used by ...

Nanoparticles (NPs) have created new ways to enhance the performance of classical biosensors in analytical sciences. NPs with unprecedented physiochemical properties can serve both as excellent carriers of bioreceptors and as signal enhancers, leading to improved assay platforms with high sensitivity and selectivity. Because enzymes play central roles in many cellular functions, specific and pr...

Sulfotransferases are enzymes that catalyze the transfer of sulfo groups from a donor, for example 3'-phosphoadenosine 5'-phosphosulfate, to an acceptor, for example the amino or hydroxyl groups of a small molecule, xenobiotic, carbohydrate, or peptide. These enzymes are important targets in the design of novel therapeutics for treatment of a variety of diseases. This review examines assays use...