PDBsum entry 3csh

Transferase

PDB id: 3csh

Contents

Protein chain

209 a.a. *

Ligands

MES ×2

LZ6 ×2

GSH ×2

SO4

Metals

_CL ×2

_CA

Waters ×627

* Residue conservation analysis

PDB id:

3csh

Name:

Transferase

Title:

Crystal structure of glutathione transferase pi in complex with the chlorambucil-glutathione conjugate

Structure:

Glutathione s-transferase p. Chain: a, b. Synonym: gst class-pi, gstp1-1. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: gstp1, faees3, gst3. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.55Å R-factor: 0.171 R-free: 0.200

Authors:

L.J.Parker

Key ref:

L.J.Parker et al. (2008). The anti-cancer drug chlorambucil as a substrate for the human polymorphic enzyme glutathione transferase P1-1: kinetic properties and crystallographic characterisation of allelic variants. J Mol Biol, 380, 131-144. PubMed id: 18511072

Date:

09-Apr-08 Release date: 01-Jul-08

Protein chains

P09211  (GSTP1_HUMAN) -  Glutathione S-transferase P from Homo sapiens

Seq: 210 a.a.

Struc: 209 a.a.

Enzyme reactions

• Enzyme class: E.C.2.5.1.18 - glutathione transferase.
• Reaction: RX + glutathione = an S-substituted glutathione + a halide anion + H⁺

RX (Bound ligand (Het Group name = LZ6) matches with 52.63% similarity) + glutathione = S-substituted glutathione + halide anion + H(+)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

Added reference

J Mol Biol 380:131-144 (2008)

PubMed id: 18511072

The anti-cancer drug chlorambucil as a substrate for the human polymorphic enzyme glutathione transferase P1-1: kinetic properties and crystallographic characterisation of allelic variants.

L.J.Parker, S.Ciccone, L.C.Italiano, A.Primavera, A.J.Oakley, C.J.Morton, N.C.Hancock, M.L.Bello, M.W.Parker.

ABSTRACT

The commonly used anti-cancer drug chlorambucil is the primary treatment for patients with chronic lymphocytic leukaemia. Chlorambucil has been shown to be detoxified by human glutathione transferase Pi (GST P1-1), an enzyme that is often found over-expressed in cancer tissues. The allelic variants of GST P1-1 are associated with differing susceptibilities to leukaemia and differ markedly in their efficiency in catalysing glutathione (GSH) conjugation reactions. Here, we perform detailed kinetic studies of the allelic variants with the aid of three representative co-substrates. We show that the differing catalytic properties of the variants are highly substrate-dependent. We show also that all variants exhibit the same temperature stability in the range 10 degrees C to 45 degrees C. We have determined the crystal structures of GST P1-1 in complex with chlorambucil and its GSH conjugate for two of these allelic variants that have different residues at positions 104 and 113. Chlorambucil is found to bind in a non-productive mode to the substrate-binding site (H-site) in the absence of GSH. This result suggests that under certain stress conditions where GSH levels are low, GST P1-1 can inactivate the drug by sequestering it from the surrounding medium. However, in the presence of GSH, chlorambucil binds in the H-site in a productive mode and undergoes a conjugation reaction with GSH present in the crystal. The crystal structure of the GSH-chlorambucil complex bound to the *C variant is identical with the *A variant ruling out the hypothesis that primary structure differences between the variants cause structural changes at the active site. Finally, we show that chlorambucil is a very poor inhibitor of the enzyme in contrast to ethacrynic acid, which binds to the enzyme in a similar fashion but can act as both substrate and inhibitor.