In order to quantitate protein in biological samples, these several methods, Bradford, Lowry, BCA, Bohlen, has limitation since the constituents of biological buffers sometimes interfere with those methods. Therefore, it is limiting their application. But don’t worry, there is still a method that could be used to estimate protein in biological samples. The method is Nitric Acid method which is based on the formation of substances, as the result of a reaction between nitric acid and protein, that can be measured by using spectrophotometer at 358 nm. read more…
Column liquid chromatography has been employed for the separation, purification, and detection of nucleic acids. Among chromatography methods provided, anion-exchange chromatography has been most commonly employed for the isolation and purification of not only oligonucleotides but also large double-stranded DNA. read more…
Some polymerase chain reaction (PCR) applications such as gene detection or typing, require little purified DNA and may be performed with crude bacterial extract. Many methods have been described for this procedure and some of them are straightforward and consist simply boiling bacterial cells in water. At this chance, we want to share the extraction method of bacterial DNA for PCR that works well with Gram-positive bacteria such as staphylococci, enterococci, and Clostridium difficile. read more…
Although Lowry method is not good enough compared to Bradford and Bicinchoninic Acid method for protein quantitation, but it is still widely used due to its acceptability to estimate protein in almost all circumstances in which protein mixtures or crude extracts are involved. Lowry method is based on the conversion of Cu2+ to Cu+ under alkaline conditions. The reactions result in a strong blue color, which depends partly on the tyrosine and tryptophan content. Sensitivity of the method is down to about 0.01 mg of protein /mL, and is best used on solutions with concentrations in the range 0.01-1.0 mg/mL of protein. If your sample contains protein less than 0.01, then you can used Bradford method (it can be used for measuring between 1 and 10 micrograms of protein, for microassay) and Bicinchoninic Acid method (it can be used for measuring between 0.5 and 10 micrograms of protein/mL, for microassay). read more…
In order to measure DNA content you can use UV Spectrophotometer with the advantages are nondestructive and allows the sample to be recovered for further analysis or manipulation. Spectrophotometry uses the fact that there is a relationship between the absorption of ultraviolet light by DNA/RNA and its concentration in a sample. In this particular posting, We try to share with you facts about the relationship between DNA/RNA with the wavelength in the Spectrophotometer assay. read more…