Helix, glyceraldehyde-3-phosphate dehydrogenase

Fig. 15. Stereo drawing of a bent helix (glyceraldehyde-phosphate dehydrogenase residues 146-161) with an internal proline. The proline ring produces steric hindrance to the straight a-helical conformation as well as having no NH group available for a hydrogen bond. A proline is the commonest way of producing a bend within a single helix, as well as occurring very frequently at the comers between helices.

Figure 2-13 (A) Stereoscopic view of the nucleotide binding domain of glyceraldehyde phosphate dehydrogenase. The enzyme is from Bacillus stearothermophilus but is homologous to the enzyme from animal sources. Residues are numbered 0-148. In this wire model all of the main chain C, O, and N atoms are shown but side chains have been omitted. The large central twisted P sheet, with strands roughly perpendicular to the page, is seen clearly hydrogen bonds are indicated by dashed lines. Helices are visible on both sides of the sheet. The coenzyme NAD+ is bound at the end of the P sheet toward the viewer. Note that the two phosphate groups in the center of the NAD+ are H-bonded to the N terminus of the helix beginning with RIO. From Skarzynski et al.llla (B) Structural formula for NAD+.

Domain 1 Greek key helix bundle Domain 2 miscellaneous antiparallel a Dehydrogenases, see Alcohol, Glyceraldehyde phosphate, Malate, or Lactate... 

Fig. 2.35. Schematic diagram of the structure of Bacillus stearothermophilus glyceraldehyde-3-phosphate dehydrogenase (according to Biesecker et aL, 1977 courtesy of J. Walker) The first domain, NAD binding domain, consists of residues 1-149 organized in two Ross-mann folds the position of NAD is indicated. In the second domain (residues 150-311), an extensive region of antiparallel p sheet form a subunit interface the S loop is formed by residues 178-201 the C-terminal helix (residues 312-333) fits into a groove in the first domain.

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