Maintenance and thermal stabilization of NADH dehydrogenase-2 conformation upon elimination of its C-terminal region

JOSEFINA M VILLEGAS; CLARISA M TORRES-BUGEAU; ROSANA CHEHÍN; MARTHA I BURGOS; GERARDO D FIDELIO; MARÍA R RINTOUL; VIVIANA A RAPISARDA

BIOCHIMIE

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2013 vol. 95 p. 382 - 387

0300-9084

Development of an artificial enzyme with activity and structure comparable to that of natural enzymes is an important goal in biological chemistry. Respiratory NADH dehydrogenase-2 (NDH-2) of Escherichia coli is a peripheral membrane-bound flavoprotein, belonging to a group with scarce structural information. By eliminating the C-terminal region of NDH-2, a water soluble version with significant enzymatic activity was previously obtained. Here, NDH-2 structural features were established, in comparison to those of the truncated version. Far-UV circular dichroism, Fourier transform infrared spectroscopy and limited proteolysis analysis showed that the overall structure of both proteins was similar at 30°C. Experimental data agree with the predicted NDH-2 structure (PDB: 1OZK). The absence of C-terminal region stabilized in ~5-10°C the truncated protein conformation. However, truncation impaired enzymatic activity at low temperatures, probably due to the weak interaction of the mutant protein with FAD cofactor.