2-Ketogluconate Kinase from Cupriavidus necator H16: Purification, Characterization, and Exploration of Its Substrate Specificity.

We have cloned, overexpressed, purified, and characterized a 2-ketogluconate kinase (2-dehydrogluconokinase, EC 2.7.1.13) from Cupriavidus necator (Ralstonia eutropha) H16. Exploration of its substrate specificity revealed that three ketoacids (2-keto-3-deoxy-d-gluconate, 2-keto-d-gulonate, and 2-keto-3-deoxy-d-gulonate) with structures close to the natural substrate (2-keto-d-gluconate) were successfully phosphorylated at an efficiency lower than or comparable to 2-ketogluconate, as depicted by the measured kinetic constant values. Eleven aldo and keto monosaccharides of different chain lengths and stereochemistries were also assayed but not found to be substrates. 2-ketogluconate-6-phosphate was synthesized at a preparative scale and was fully characterized for the first time.

Direct and highly sensitive measurement of fluorescent molecules in bulk solutions using flow cytometry.

Utilizing flow cytometry to monitor progress of bulk biochemical reactions and concentration of chemical species normally relies on the utilization of cells carrying intrinsic fluorescence or modified beads. We present a method for a simple measurement of the fluorescent marker molecule fluorescein and GFPuv in bulk solutions with high sensitivity using a CytoFLEX flow cytometer and without the need for modified beads. Polystyrene beads were used to trigger measurements based on their high scatter signal, to detect the fluorescence signal from two different fluorophores present in the sample solution. We report sensitivities of 33 pg/mL for fluorescein and 50 ng/mL for GFPuv. This method is comparable in sensitivity to a typical spectrometric fluorescence assay tested with fluorescein, and approximately ten times more sensitive for the measurement of GFPuv. PEG was added to the sample at a low concentration of 0.001% (w/v) to block unspecific GFPuv binding to the beads. The method was further applied to measure the GFPuv concentration in crude cell lysate samples used for cell free protein expression. An advantage of this method over spectrometric assays is the ability to differentiate signal subpopulations in the sample based on their individual fluorescence intensities.

Safety of clomiphene citrate: a literature review.

Clomiphene citrate (CC) is a nonsteroidal compound and induces ovulation indirectly. The wide usage of the CC raises a question; is it safe or not? In the light of this question, this review aimed to highlight all researches and insights into the association between the use of CC and risk of genotoxicity, cytotoxicity, embryotoxicity, teratogenicity and risk of different cancer types. We conducted a MEDLINE/PubMed, Scopus, Web of Science, Google Scholar search. After a careful screening process of all authors, 32 of these articles were considered as appropriate, and reviewed. Our evaluations showed that CC has genotoxic, cytotoxic, embryotoxic and teratogenic properties. There is no association between the use of CC and risk of ovarian, breast, uterine, cervix, endometrium, lung, colorectal cancer, and lymphoma. However, risk increased especially after 6 cycles of use and especially in nulligravid women. The use of CC should be restricted to 6 cycles. Moreover, malignant melanoma and thyroid cancer risk was found to be higher among CC treated women in almost all studies. Further works should be conducted especially in animal models to assess its risk features.

Evaluation of the genotoxicity of clomiphene citrate.

Clomiphene citrate (CC) is a selective estrogen-receptor modulator that is primarily used to enhance follicular development in women receiving in vitro fertilization (IVF) treatment. Although some studies suggested large increases in ovarian cancer risk related to fertility medications, this association has not been confirmed in other studies. Whether there could be a residual, small risk is still an open question. It is known that genomic instability and multiple genetic changes may be required in carcinogenesis. Genomic instability such as single-base changes, chromosomal rearrangements or aneuploidy may accelerate this process. Genomic instability is not only central to carcinogenesis, but it is also a factor in some neurodegenerative diseases such as amyotrophic lateral sclerosis or the neuromuscular disease myotonic dystrophy. For these reasons, this study was planned to examine genotoxic effects of CC in human lymphocytes by use of the chromosome aberration (CA) assay, the micronucleus (MN) test, the comet assay, and the test for bacterial mutagenicity in Salmonella typhimurium strains TA98 and TA100 (Ames test). Concentrations of 0.40, 0.80, 1.60, and 3.20µg/ml of CC significantly increased the frequency of chromosomal aberrations (p<0.01 and p<0.001) and micronuclei (p<0.05, p<0.01 and p<0.001) in cultured human lymphocytes, and of DNA damage (tail length, p<0.05, except 0.80µg/ml) in isolated lymphocytes compared with their respective controls. The highest CC concentration at 24h and highest two concentrations after the 48-h treatment significantly decreased the mitotic index. The Ames test showed that the concentrations of CC used in this study induced neither base-pair substitutions nor frame-shift mutations in S. typhimurium strains TA98 and TA100.