Structure

Glyceraldehyde 3-phosphate dehydrogenase is made up of four identical subunits. The first molecule of NAD to bind causes the subunits to become unsymmetrical; the symmetry returns when all four subunits have NAD bound.⁹ The total molecular weight of the enzyme is 145000. The enzyme structure and function are conserved throughout many different species.⁵ GAPDH has two folding domains. The first domain makes up the majority of the NAD binding site and is from residues 0-148.¹ The fold in this domain is a b-a-b pattern with a central sheet covered on both sides by helices. The second domain comprises residues 149-333 and contains

Show secondary structure Show chain a many side chains that are involved with the catalysis of

Show b sheets Show a helix the reaction.¹This domain contains many antiparallel b

sheets that form an interface between the equivalent region of the P-axis related subunit. The second domain also contains the irregular S-loop from residues 178-201. The S-loop is in contact with the NAD as well as several amino acids across the P-axis of symmetry. This enzyme also exhibits the Rossman fold within its active site.²This is an a/b structure that has a central b sheet flanked by a layer of a-helices. This fold is common to many different dehydrogenases. This enzyme also contains the ADP binding fingerprint that is common among NAD dependent dehydrogenases.³ This fingerprint is an invariant Asp residue at position 32 of the C-terminus of the second b-sheet.

The most extensive intersubunit interactions are formed by the P-axis related monomers. These involve highly conserved residues within the anti-parallel sheets of the active site.⁸ There are also several hydrogen bonds and intersubunit salt bridges that help to stabilize the tertiary and quaternary structure of the enzyme.⁴ Arg-194 forms a salt bridge with Asp-293 of the P-axis related subunit.¹ There are also important interactions between the R-axis related monomers. These hydrophophobic interactions create the S-loop region in the active sites. A majority of the intermolecular contacts involve the S-loop and the NAD binding domain.⁸

	Glyceraldehyde 3-phosphate dehydrogenase is made up of four identical subunits. The first molecule of NAD to bind causes the subunits to become unsymmetrical; the symmetry returns when all four subunits have NAD bound.⁹ The total molecular weight of the enzyme is 145000. The enzyme structure and function are conserved throughout many different species.⁵ GAPDH has two folding domains. The first domain makes up the majority of the NAD binding site and is from residues 0-148.¹ The fold in this domain is a b-a-b pattern with a central sheet covered on both sides by helices. The second domain comprises residues 149-333 and contains
Show secondary structure Show chain a	many side chains that are involved with the catalysis of
Show b sheets Show a helix	the reaction.¹This domain contains many antiparallel b