A useful propionate cofactor enhancing activity for organic solvent-tolerant recombinant metal-free bromoperoxidase (perhydrolase) from Streptomyces aureofaciens
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Authors: China, Hideyasu; Ogino, Hiroyasu
Abstract
The oxidative brominating activity of an organic solvent-tolerant recombinant metal-free bromoperoxidase BPO-Al with C-terminal His-tag (rBPO-A1), from Streptomyces aureofaciens found to depend on various additives. These included carboxylic acids, used as cofactors and alcohols, used as water-miscible organic solvents. Enzyme activity was significantly enhanced by using propanoic acid (PA) as a cofactor, which had a high Log D at pH 5.0 and ethylene glycol with a low Log P. The positional specificity of oxidative hydroxybromination for olefins, using rBPO-A1 and PA in the presence of methanol, was higher compared to a non-enzymatic reaction using peracetic acid. The oxidative bromination step, occurring after enzymatic peroxidation step, is suggested to be pseudoenzymatic. (C) 2019 Elsevier Inc. All rights reserved.
Generation of fully functional fluorescent fusion proteins to gain insights into ABCC6 biology
FEBS LETTERS
Authors: Szeri, Flora; Niaziorimi, Fatemeh; Donnelly, Sylvia; Orndorff, Joseph; Wetering, Koen
Abstract
ABCC6 mediates release of ATP from hepatocytes into the blood. Extracellularly, ATP is converted into the mineralization inhibitor pyrophosphate. Consequently, inactivating mutations in ABCC6 give low plasma pyrophosphate and underlie the ectopic mineralization disorder pseudoxanthoma elasticum. How ABCC6 mediates cellular ATP release is still unknown. Fluorescent ABCC6 fusion proteins would allow mechanistic studies, but fluorophores attached to the ABCC6 N- or C-terminus result in intracellular retention and degradation. Here we describe that intramolecular introduction of fluorophores yields fully functional ABCC6 fusion proteins. A corresponding ABCC6 variant in which the catalytic glutamate of the second nucleotide binding domain was mutated, correctly routed to the plasma membrane but was inactive. Finally, N-terminal His(10) or FLAG tags did not affect activity of the fusion proteins, allowing their purification for biochemical characterization.