Search

The self-assembly layer consisting of fusion protein is investigated in molecular-scale for the construction of bioelectronic device. Cytochrome b562 and green fluorescent protein were used as an electron acceptor and a sensitizer in the molecular layer by mimicking the photosynthesis. Self-assembled monolayer of fusion protein was formed on Au coated glass. The formation of fusion protein layer onto the Au substrate was observed by the surface plasmon resonance measurement. The surface of fusion protein layer was observed and analyzed by the scanning tunneling microscopy observation. For embodiment of the molecular electronic device, molecular arrays of fusion protein SA layer were formed by micro contact printing. Surface charge distribution of fusion protein SA layer was measured to confirm an electrical conductivity by electrostatic force microscopy observation.

In recent years, the importance of proteomic works, such as protein expression, detection and identification, has grown in the fields of proteomic and diagnostic research. This is because complete genome sequences of humans, and other organisms, progress as cellular processing and controlling are performed by proteins as well as DNA or RNA. However, conventional protein analyses are time-consuming; therefore, high throughput protein analysis methods, which allow fast, direct and quantitative detection, are needed. These are so-called protein microarrays or protein chips, which have been developed to fulfill the need for high-throughput protein analyses. Although protein arrays are still in their infancy, technical development in immobilizing proteins in their native conformation on arrays, and the development of more sensitive detection methods, will facilitate the rapid deployment of protein arrays as high-throughput protein assay tools in proteomics and diagnostics. This review summarizes the basic technologies that are needed in the fabrication of protein arrays and their recent applications.

For the production of oil-desulfurizing biocatalyst, a two-stage fermentation strategy was adopted, in which the cell growth stage and desulfurization activity induction stage were separated. Sucrose was found to be the optimal carbon source for the growth of Gordonia nitida CYKS1. Magnesium sulfate was selected to be the sulfur source in the cell growth stage. The optimal ranges of sucrose and magnesium sulfate were 10-50 and 1-2.5 g x L(-1), respectively. Such a broad optimal concentration of sucrose made the fed-batch culture easy, while the sucrose concentration was maintained between 10-20 g x L(-1) in the actual operation. As a result, 92.6 g x L(-1) of cell mass was acquired by 120 h of fed-batch culture. This cell mass was over three times higher than a previously reported result, though the strain used was different. The desulfurization activity of the harvested cells from the first stage culture was induced by batch cultivation with dibenzothiophene as the sole sulfur source. The optimal induction time was found to be about 4 h. The resting-cell biocatalyst made from the induced cells was applied for the deep desulfurization of a diesel oil. It was observed that the sulfur content of the diesel oil decreased from 250 mg-sulfur x L-oil(-1) to as low as 61 mg-sulfur x L-oil(-1) in 20 h. It implied that the biocatalyst developed in this study had a good potential to be applied to a deep desulfurization process to produce ultra-low-sulfur fuel oils.

Pseudomonas aeruginosa Azurin is a metalloprotein of 14 kDa with copper ion in its active site. Protein film formation onto the substrate was performed by the self-assembly technique. In order to make molecule assembled layer onto the gold substrate, Azurin was cross-linked with N-succinimidyl-3-(2-pyridyldithio)-propionate (SPDP). SPDP have both a -thiol group to assembly with gold substrate and a linking part to assembly with protein. We detected optimized condition to make a protein film using Surface Plasmon Resonance (SPR). The surface structure of adsorbed Azurin film onto the gold surface was analyzed by scanning tunneling microscope (STM).