During glycolysis, gyceraldehyde-3-phosphate dehydrogenase converts glyceraldehyde-3-phosphate (G-3-P) to 1,3-bisphosphoglycerate (1,3-BGP) through oxidative phosphorylation. NAD+ is oxidized to NADH when a Pi is exchanged for a hydrogen on the carbonyl carbon of G-3-P thus converting G-3-P to 1,3-BGP.

Steps of Glyceraldehyde-3-Phosphate Dehydrogenase Reaction Mechanism

I. SH group of cysteine is activated by histidine

II. SH attacks CO, H+e- are transferred to NAD

III.Thio-ester intermediate

IV. Thio-ester attacked by Pi

Molecular Model of Glyceraldehyde-3-Phosphate Dehydrogenase

Glyceraldehyde-3-Phosphate Dehydrogenase is a 160kD protein that functions as a tetramer. Each subunit contains 360 residues and is comprised of two-domains.

Four Subunits

There are 11 alpha helices and 17 beta sheets in each subunit.

Secondary Structure

NAD within Glyceraldehyde-3-Phosphate Dehydrogenase

Glyceraldehyde-3-Phosphate Dehydrogenase oxidately phosphorylates G-3-P into 1,3-BGP. The acceptor of electrons is NAD+. The reducton of NAD+ proceeds by the enzymatic transfer of a hydride ion from the aldehyde group of G-3-P to the nicotinamide ring of NAD, yielding the reduced coenzyme NADH.

NAD+ Binding Zoom Catalytic Region

Display entire structure

Use the following commands to adjust the molecular models position. You can also you the mouse to rotate the molecule by clicking on the structure.

Reset Position

Rotate: Y 90°   Y -90°
X 90°   X -90°

Distances:  Width (Å)   Height (Å)

Background Color: White Blue Black

NAD Home Introduction Biosynthesis of NAD Example 1: Alcohol Dehydrogenase Example III: Lactate Dehydrogenase References