Proteins from extremophiles as stable tools for advanced biotechnological applications of high social interest

Abstract

Extremophiles are micro-organisms adapted to survive in ecological niches defined as 'extreme' for humans and characterized by the presence of adverse environmental conditions, such as high or low temperatures, extreme values of pH, high salt concentrations or high pressure. Biomolecules isolated from extremophiles possess extraordinary properties and, in particular, proteins isolated from extremophiles represent unique biomolecules that function under severe conditions, comparable to those prevailing in various industrial processes. In this article, we will review some examples of recent applications of thermophilic proteins for the development of a new class of fluorescence non-consuming substrate biosensors for monitoring the levels of two analytes of high social interest, such as glucose and sodium.

Figure 1

Polarization sensing with a reference solution.

Figure 2

Stability of BSGK and YHK at room temperature. Fluorescence measurements were performed at room temperature. Ex=290 nm; Em=340 nm.

Figure 3

o-Nitrophenyl-β-d-glucopyranoside (ONPG).

Figure 4

Effect of glucose on the intensity emission of BSGK in the presence of ONPG. The excitation was at 290 nm and the emission was recorded at 340 nm. [BSGK]=3 μM.

Figure 5

Effect of glucose on the polarization spectra of BSGK in the presence of ONPG. Excitation was at 290 nm. [BSGK]=3 μM.

Figure 6

ANS-labelled GD fluorescence intensity in the presence of different concentrations of acetone. [GD]=3 μM; [ANS]=4 μM. The excitation was at 370 nm and the emission was monitored at 510 nm.

Figure 7

Emission spectra of ANS-labelled GD in the presence of 3% acetone and at different concentrations of glucose. [GD]=3 μM; [ANS]=4 μM. Increase of glucose concentration over 70 mM does not introduce further changes in fluorescence intensity.

Figure 8

Frequency-domain intensity decay of ANS-labelled GD with 3% acetone in the absence and presence of glucose.

Figure 9

Effect of glucose on the polarization of GD in the presence of 3% acetone. The excitation was at 370 nm and the emission was recorded at 470 nm. [GD]=3 μM; [ANS]=4 μM.

Figure 10

Steady-state fluorescence titration curves of pyruvate kinase from Bacillus acidocaldarius.