An integrated prediction of secondary, tertiary and quaternary structure of glucose dehydrogenase

Abstract

Based on homology of partial sequences, on physico~hemi~al evidence and on studies using chemical modification, we came to the tentative conclusion that tetrameric glucose dehydrogenases from Bacillus megaterium and B. subtilis should have a structure closely related to that of lactate dehydrogenase. The overall homology of primary structures was found to be very low, however, and independent predictions of secondary structure produced a clearly different pattern of p-strands and cr-helices. We nevertheless tried a manual prediction based on the hydrophobic nature of internal B-sheet and on the amphiphili~ character of external helices. This treatment led to the identification of analogues of all the b-strands present in lactate dehydrogenase with the exception of j-X. Six amphiphilic helices were identified corresponding to uB, ctC, uD, cllF, u2F and a3G in lactate dehydrogenase. Conserved functional residues were found at analogous positions. The Q and R intersubunit contacts could be identified and partial proteolysis was found to occur on the outer surface of the tetramer. The structure was found to explain the better binding of NADP as compared to NAD' and offered a rationalization of the role of the essential lysine at position 201.

Identification and isolation of glucose dehydrogenase genes of Bacillus megaterium M1286 and their expression in Escherichia coli

“…On the other hand a very high homology of 93 -95% extends over the last 110 amino acids, the region in which the substrate-binding area is expected (Jany, personal communication). Amino acid Gly-20, a residue with functional importance for binding of NAD+ [24], as well as amino acids His-148, Lys-201 and Tyr-254 [4], which are proposed as being part of the active site, are strictly conserved in all three enzymes. In contrast to this, exchanges at position 149 -151 or even a loss of amino acid residues in this region seem to be allowed (Fig.…”

Enzymatic properties of isozymes and variants of glucose dehydrogenase from Bacillus megaterium

“…NADP and n-glucose. When NAD was used as a coenzyme, the NAU concentration range was 0.4-2 mM and the D-glucose range was [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Fig. 2b shows that the effects of pH on the stability of these enzymes are a little different from each other.…”

Glucose Transforming Enzymes

“…The complete amino acid sequence of the B. megaterium and B. subtilis enzyme have been determined (Fig. 5, Jany et al, 1984) and a prediction of secondary, tertiary and quaternary structure has been proposed (Hones et al, 1987). The active tetrameric GDH from B. megaterium was rapidly inactivated upon reaction with tetranitromethane by nitration of tyrosine 254, which was essential for the catalytic activity.…”