PDBsum entry 1aql

Hydrolase

PDB id: 1aql

Contents

Protein chains

532 a.a. *

Ligands

NAG ×2

TCH ×4

* Residue conservation analysis

PDB id:

1aql

Name:

Hydrolase

Title:

Crystal structure of bovine bile-salt activated lipase complexed with taurocholate

Structure:

Bile-salt activated lipase. Chain: a, b. Synonym: carboxyl ester lipase, sterol esterase, cholesterol esterase, pancreatic lysophospholipase. Ec: 3.1.1.13

Source:

Bos taurus. Cattle. Organism_taxid: 9913. Organ: pancreas

Resolution:

2.80Å R-factor: 0.211 R-free: 0.275

Authors:

X.Wang,X.Zhang

Key ref:

X.Wang et al. (1997). The crystal structure of bovine bile salt activated lipase: insights into the bile salt activation mechanism. Structure, 5, 1209-1218. PubMed id: 9331420 DOI: 10.1016/S0969-2126(97)00271-2

Date:

30-Jul-97 Release date: 05-Aug-98

Protein chains

P30122  (CEL_BOVIN) -  Bile salt-activated lipase (Fragment) from Bos taurus

Seq: 597 a.a.

Struc: 532 a.a.

Enzyme reactions

• Enzyme class 2: E.C.3.1.1.13 - sterol esterase.
• Reaction: a sterol ester + H2O = a sterol + a fatty acid + H⁺

sterol ester + H2O = sterol + fatty acid (Bound ligand (Het Group name = TCH) matches with 51.43% similarity) + H(+)

• Enzyme class 3: E.C.3.1.1.3 - triacylglycerol lipase.
• Reaction: a triacylglycerol + H2O = a diacylglycerol + a fatty acid + H⁺
• Enzyme class 4: E.C.3.1.1.6 - acetylesterase.
• Reaction: an acetyl ester + H2O = an aliphatic alcohol + acetate + H⁺

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

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

reference

DOI no: 10.1016/S0969-2126(97)00271-2

Structure 5:1209-1218 (1997)

PubMed id: 9331420

The crystal structure of bovine bile salt activated lipase: insights into the bile salt activation mechanism.

X.Wang, C.S.Wang, J.Tang, F.Dyda, X.C.Zhang.

ABSTRACT

BACKGROUND: The intestinally located pancreatic enzyme, bile salt activated lipase (BAL), possesses unique activities for digesting different kinds of lipids. It also differs from other lipases in a requirement of bile salts for activity. A structure-based explanation for these unique properties has not been reached so far due to the absence of a three-dimensional structure. RESULTS: The crystal structures of bovine BAL and its complex with taurocholate have been determined at 2.8 A resolution. The overall structure of BAL belongs to the alpha/beta hydrolase fold family. Two bile salt binding sites were found in each BAL molecule within the BAL-taurocholate complex structure. One of these sites is located close to a hairpin loop near the active site. Upon the binding of taurocholate, this loop becomes less mobile and assumes a different conformation. The other bile salt binding site is located remote from the active site. In both structures, BAL forms similar dimers with the active sites facing each other. CONCLUSIONS: Bile salts activate BAL by binding to a relatively short ten-residue loop near the active site, and stabilize the loop in an open conformation. Presumably, this conformational change leads to the formation of the substrate-binding site, as suggested from kinetic data. The BAL dimer observed in the crystal structure may also play a functional role under physiological conditions.

Selected figure(s)

Figure 2.
Figure 2. Stereo view of the structural comparison of apo-BAL and GCL around their active sites. The Ca trace of the apo-BAL structure is shown in magenta; the Ca trace of GCL is shown in blue. Selected residues from BAL are labeled in red. Also included are the catalytic triad residues from the two structures, which are superimposed with each other.

The above figure is reprinted by permission from Cell Press: Structure (1997, 5, 1209-1218) copyright 1997.

Figure was selected by an automated process.