Protein Expression Prokaryotic cells A. tumefaciens

Get tips on using Expi293™ Expression System Kit to perform Protein expression and purification Mammalian cells - HEK 293 AT1R

Get tips on using Expi293™ Expression System Kit to perform Protein expression and purification Mammalian cells - HEK 293 ECD

Get tips on using heat shock protein family A (Hsp70) member 5 to perform siRNA / miRNA gene silencing Human - PC3 (human prostate cancer cell line) HSPA5 (GRP78)

Get tips on using Expi293™ Expression System Kit to perform Protein expression and purification Mammalian cells - HEK 293 Mt-PA

Get tips on using pcDNA™3.1 (+) Mammalian Expression Vector to perform Protein expression and purification Mammalian cells - CHO-K1 sRAGE

Get tips on using Bac-to-Bac™ Baculovirus Expression System to perform Protein expression and purification Insect cells - Sf9 Drosha

Get tips on using Expi293™ Expression System Kit to perform Protein expression and purification Mammalian cells - HEK 293 HER2 leader peptide

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.

I am currently using a recombinant protein which shows metal-dependent DNase activity. Is it possible to pinpoint the source of the DNase activity after protein purification? More specifically, can I ensure that the DNase activity is not because of nuclease contamination from the E.coli that might have persisted and passed with the protein of interest during purification?

Get tips on using pPICZα A, B, & C Pichia Vectors to perform Protein expression and purification Yeast - Pichia pastoris hmPRα