Protein concentration and electrophoresis
The protein concentration was determined by absorbance measurements at 280 nm using a ND-1000 spectrophotometer from Fischer scientific. The purity was judged by SDS-PAGE on polyacrylamide gels (4–20% from Biorad or 4–12% from Nupage) after heat denaturation in the presence of DTT. Gels were stained/destained with Instant Blue from Expedeon.