protein-isolation-bacteria-escherichia-coli

Protein isolation is a technique that involves isolation and/ or purification of protein from cells or tissues via chromatography or electrophoresis. The major challenges in protein isolation include: 1. The concentration of proteins in cells is variable and tends to be small for some intracellular proteins. Unlike nucleic acids, proteins cannot be amplified. 2. Proteins are more unstable than nucleic acids. They are easily denatured under suboptimal temperature, pH or salt concentrations. 3. Finally, no generalized technique/protocol can be applied for protein isolation. Proteins may have different electrostatic (number of positively or negatively charged amino acids) or hydrophobic properties. Therefore, protein purification requires multiple steps depending on their charge (a negatively charged resin/column for positively charged proteins and vice-versa), dissolution (using detergents) and unlike in the case of DNA and RNA, instead of using salts, proteins should be isolated by isoelectric precipitation.

Generally isolating RNA from Gram-negative bacteria is easy, however keeping your working environment clean and RNase free (use RNase inhibitor) is essential. Some common points to keep in mind: a) Use fresh samples for isolation or store them by freezing in RNA stabilizing buffer until use. b) Choose the bacterial input amounts carefully, to ensure buffer volumes are adequate and not to overload the columns.