Recombinant S-adenosylhomocysteine hydrolase from Thermotoga maritima: cloning, overexpression, characterization, and thermal purification studies

S-Adenosylhomocysteine hydrolase (SAHase) encoded by sahase gene is a determinant when catalyzing the reversible conversion of adenosine and homocysteine to S-adenosylhomocysteine in most living organisms. The sahase gene was isolated from the genome of the highly thermostable anaerobic bacteria Thermotoga maritima, and then it was cloned, characterized, overexpressed using Escherichia coli, and partially purified by thermal precipitation. The thermal purification of the recombinant SAHase resulted in changes in the circular dichroism spectra. As a result of this analysis, it was possible to determine the structural changes in the composition of the α-helix and β-sheet content of the recombinant enzyme after purification. Moreover, a predicted secondary structure and 3D structural model was rendered by comparative molecular modeling to further understand the molecular function of this protein including its attractive biotechnological use.

Intein-triggered artificial protein hydrogels that support the immobilization of bioactive proteins

Protein hydrogels have important applications in tissue engineering, drug delivery, and biofabrication. We present the development of a novel self-assembling protein hydrogel triggered by mixing two soluble protein block copolymers, each containing one half of a split intein. Mixing these building blocks initiates an intein trans-splicing reaction that yields a hydrogel that is highly stable over a wide range of pH (6-10) and temperature (4-50 °C), instantaneously recovers its mechanical properties after shear-induced breakdown, and is compatible with both aqueous and organic solvents. Incorporating a "docking station" peptide into the hydrogel building blocks enables simple and stable immobilization of docking protein-fused bioactive proteins in the hydrogel. This intein-triggered protein hydrogel technology opens new avenues for both in vitro metabolic pathway construction and functional/biocompatible tissue engineering scaffolds and provides a convenient platform for immobilizing enzymes in industrial biocatalysis.