6MIS image
Deposition Date 2018-09-20
Release Date 2018-10-03
Last Version Date 2024-11-20
Entry Detail
PDB ID:
6MIS
Title:
Native ananain in complex with E-64
Biological Source:
Source Organism:
Ananas comosus (Taxon ID: 4615)
Method Details:
Experimental Method:
Resolution:
1.98 Å
R-Value Free:
0.22
R-Value Work:
0.19
R-Value Observed:
0.19
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:Ananain
Gene (Uniprot):AN1
Chain IDs:A, B
Chain Length:215
Number of Molecules:2
Biological Source:Ananas comosus
Primary Citation
Determination of the crystal structure and substrate specificity of ananain.
Biochimie 166 194 202 (2019)
PMID: 31306685 DOI: 10.1016/j.biochi.2019.07.011

Abstact

Ananain (EC 3.4.22.31) accounts for less than 10% of the total enzyme in the crude pineapple stem extract known as bromelain, yet yields the majority of the proteolytic activity of bromelain. Despite a high degree of sequence identity between ananain and stem bromelain, the most abundant bromelain cysteine protease, ananain displays distinct chemical properties, substrate preference and inhibitory profile compared to stem bromelain. A tripeptidyl substrate library (REPLi) was used to further characterize the substrate specificity of ananain and identified an optimal substrate for cleavage by ananain. The optimal tripeptide, PLQ, yielded a high kcat/Km value of 1.7 x 106 M-1s-1, with cleavage confirmed to occur after the Gln residue. Crystal structures of unbound ananain and an inhibitory complex of ananain and E-64, solved at 1.73 and 1.98 Å, respectively, revealed a geometrically flat and open S1 subsite for ananain. This subsite accommodates diverse P1 substrate residues, while a narrow and deep hydrophobic pocket-like S2 subsite would accommodate a non-polar P2 residue, such as the preferred Leu residue observed in the specificity studies. A further illustration of the atomic interactions between E-64 and ananain explains the high inhibitory efficiency of E-64 toward ananain. These data reveal the first in depth structural and functional data for ananain and provide a basis for further study of the natural properties of the enzyme.

Legend

Protein

Chemical

Disease

Primary Citation of related structures