 |
PDBsum entry 1euf
|
|
|
|
|
 |
Contents |
 |
|
|
|
|
|
|
|
|
|
|
|
|
* Residue conservation analysis
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Crystal structure of bovine duodenase, A serine protease, With dual trypsin and chymotrypsin-Like specificities.
|
|
|
Authors
|
|
V.Z.Pletnev,
T.S.Zamolodchikova,
W.A.Pangborn,
W.L.Duax.
|
|
|
Ref.
|
|
Proteins, 2000,
41,
8.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
The three-dimensional structure of duodenase, a serine protease from bovine
duodenum mucosa, has been determined at 2.4A resolution. The enzyme, which has
both trypsin-like and chymotrypsin-like activities, most closely resembles human
cathepsin G with which it shares 57% sequence identity and similar specificity.
The catalytic Ser195 in duodenase adopts the energetically favored conformation
typical of serine proteinases and unlike the strained state typical of
lipase/esterases. Of several waters in the active site of duodenase, the one
associated with Ser214 is found in all serine proteinases and most
lipase/esterases. The conservation of the Ser214 residue in serine proteinase,
its presence in the active site, and participation in a hydrogen water network
involving the catalytic triad (His57, Asp107, and Ser195) argues for its having
an important role in the mechanism of action. It may be referred to as a fourth
member of the catalytic triad. Duodenase is one of a growing family of enzymes
that possesses trypsin-like and chymotrypsin-like activity. Not long ago, these
activities were considered to be mutually exclusive. Computer modeling reveals
that the S1 subsite of duodenase has structural features compatible with
effective accommodation of P1 residues typical of trypsin (Arg/Lys) and
chymotrypsin (Tyr/Phe) substrates. The determination of structural features
associated with functional variation in the enzyme family may permit design of
enzymes with a specific ratio of trypsin and chymotrypsin activities.
|
|
|
|
|
|
|
|
Figure 1.
Figure 1. A ribbon representation of three-dimensional
structure of duodenase with catalytic triad His57, Asp102, and
Ser195 shown in red and disulfide bonds between residues 42:58,
136:201, and 168:182 in brown.  -strands
(blue) and helices (magenta) are shown by arrow and helix
representation, respectively.
|
|
Figure 2.
Figure 2. A scheme of duodenase secondary structure topology.
-strand
and helix elements are presented by arrows and helices,
respectively. Only one hydrogen nonbonded residue in b
conformation is allowed for inclusion at -strand
termini.
|
|
|
|
|
|
The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2000,
41,
8-0)
copyright 2000.
|
|
|
|
|
|
|
