Proteorhodopsin characterization based on metal–insulator–metal structure technique

Opsin vs opsin: New materials for biotechnological applications

“…Furthermore, both proteins exhibit an increase in the current intensity in the presence of a visible light. 12,14 So far, the interpretation of experimental results, made in the framework of the INPA model, has been satisfactory when applied to bR. As a matter of fact, most of I-V measurements have been conducted on monolayers of this protein Therefore, it has been possible to calibrate the network parameters in order to reproduce on a very wide range (more than six orders of magnitude) the current responses.…”

“…Accordingly, it requires extreme skill in the experimental setup 13 and often only the DT regime is observed. 12,14 The way followed to get the FN regime has been to perform nanometric measurements, i.e., onto nanometric sized samples and resolving very low (from 0.3 picoampere to about 10 nanoampere) current intensities. Due to the Joule heating, larger samples do not allow this kind of measurements.…”

“…This raises the question of a possible interchange of these proteins in specific applications, i.e., when the expected responses are more related to the topological properties than to the functional properties. As matter of fact, it has to be emphasized that opsins by prokaryotes are more easier to be produced and used in vitro, [12][13][14] with respect to proteins by eukaryotes, 15 and this of course is of interest for applications.…”

Investigations on the electrical current-voltage response in protein light receptors

“…First measurements of I-V characteristics in pR were reported in Ref. [2]. The experiment was performed on a thin-film device with a contact distance of 50 µm, just about 10 4 times longer than the bR nanolayers used in the previous experiments [3,1].…”

Reaction Center of Rhodobacter Sphaeroides, a Photoactive Protein for pH Sensing: A Theoretical Investigation of Charge Transport Properties

“…When these conditions change also the output changes, often in a way which is poorly appreciable at the naked eye but which can induce severe transformation in the protein functioning. Photosensitive proteins are quite interesting in this respect, because the topological transformation they undergo after they have absorbed light energy can appear quite small but produce an indisputable change in their functioning, which has been detected, for example, as an increase of their conductance [15][16][17]. Due to the difficulty in performing protein crystallization and analysis, available data refer often to a specific combination of environmental conditions and a comparative analysis of the effects of tuning these data is quite difficult to be found.…”