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Description |
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Leishmania mexicana Phosphoglycerate
mutase
Phosphoglycerate mutase from Leishmania mexicana. A ball-and-stick
representation of the substrate 3-phosphoglycerate is shown at the
active site that is located between the domains of this monomeric
enzyme. The sphere at the active site is a cobalt ion, and is required
for activity. The other sphere near the periphery of the enzyme is
a sodium ion that may help to stabilise the enzyme.
This enzyme is a particularly good target for structure-based drug
design because it is not homologous with the corresponding PGAM from
the human host. These two enzymes share no common structural or mechanistic
features.
See more information
about structure
Link to Protein Database: http://www.rcsb.org/pdb/
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Trypanosoma brucei - Phosphofructokinase
The tetrameric structure of phosphofructokinase from Trypanosoma brucei.
The N-terminal domains shown at the left and right of the figure appear
to function as embracing arms that stabilise the quaternary structure.
Compare this figure with that of a single subunit where some of the
features that distinguish the parasite enzyme from those of its human
host are highlighted.
See more information about structure
Link to Protein Database: http://www.rcsb.org/pdb/ |
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Leishmania mexicana - pyruvate kinase
Comparison of the structures of Leishmania mexicana pyruvate
kinase in its inactive T-state (blue) with that of a putative R-state (yellow).
It can be seen that the major differences occur in the B-domain at the
bottom of the diagram. The active site is located between the B-domain
and the adjacent A-domain that is folded into an 8-fold alpha-beta barrel.
The parasite and human enzymes have different allosteric activators,
and the consequential differences at the effector site (in the C-domain
top left of diagram) provide opportunities for the development of parasite-specific
inhibitors.
See
more information about structure
Link to Protein Database: http://www.rcsb.org/pdb/
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Flavocytochrome c3 (fumarate
reductase)
Flavocytochrome c3 from the bacterium Shewanella
frigidimarina is
a soluble, periplasmic fumarate reductase that supports anaerobic respiration
with fumarate. The enzyme is composed of a tetraheme c-type cytochrome
domain that delivers electrons to the active site FAD. The active site
is at the interface of the flavin-binding and clamp domains, which
are conserved in the catalytic subunits of membrane-bound fumarate
reductases and succinate dehydrogenases.
See
more information about structure
Link to Protein Database: http://www.rcsb.org/pdb/
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Thermostable Lipase
We describe the first lipase structure from a thermophilic organism.
It shares less than 20 percent amino acid sequence identity with other
lipases for which there are crystal structures, and shows significant
insertions compared with the typical alpha/beta hydrolase canonical
fold. The structure contains a zinc-binding site which is unique among
all lipases with known structures, and which may play a role in enhancing
thermal stability. Zinc binding is mediated by two histidine and two
aspartic acid residues. These residues are present in comparable positions
in the sequences of certain lipases for which there is as yet no crystal
structural information, such as those from Staphylococcal species and
Arabidopsis thaliana. The structure of Bacillus stearothermophilus P1
lipase provides a template for other thermostable lipases, and offers
insight into mechanisms used to enhance thermal stability which may
be of commercial value in engineering lipases for industrial uses.
See
more information about structure
Link to Protein Database: http://www.rcsb.org/pdb/ |
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Ocr from bacteriophage T7
We have solved, by X-ray crystallography to a resolution of 1.8 A,
the structure of a protein capable of mimicking approximately 20 base
pairs of B-form DNA. This ocr protein, encoded by gene 0.3 of bacteriophage
T7, mimics the size and shape of a bent DNA molecule and the arrangement
of negative charges along the phosphate backbone of B-form DNA. We also
demonstrate that ocr is an efficient inhibitor in vivo of all known
families of the complex type I DNA restriction enzymes. Using atomic
force microscopy, we have also observed that type 1 enzymes induce a
bend in DNA of similar magnitude to the bend in the ocr molecule. This
first structure of an antirestriction protein demonstrates the construction
of structural mimetics of long segments of B-form DNA.
See
more information about structure
Link to Protein Database: http://www.rcsb.org/pdb/ |
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Cyclophilin 40
The large immunophilin family consists of domains of cyclophilin or
FK506 binding protein linked to a tetratricopeptide (TPR) domain. They
are intimately associated with steroid receptor complexes and bind to
the C-terminal domain of Hsp90 via the TPR domain. The competitive binding
of specific large immunophilins and other TPR-Hsp90 proteins provides
a regulatory mechanism for Hsp90 chaperone activity. We have solved
the X-ray structures of monoclinic and tetragonal forms of Cyp40. In
the monoclinic form, the TPR domain consists of seven helices of variable
length incorporating three TPR motifs, which provide a convincing binding
surface for the Hsp90 C-terminal MEEVD sequence. The C-terminal residues
of Cyp40 protrude out beyond the body of the TPR domain to form a charged
helix-the putative calmodulin binding site. However, in the tetragonal
form, two of the TPR helices have straightened out to form one extended
helix, providing a dramatically different conformation of the molecule.
The X-ray structures are consistent with the role of Cyclophilin 40
as a multifunctional signaling protein involved in a variety of protein-protein
interactions. The intermolecular helix-helix interactions in the tetragonal
form mimic the intramolecular interactions found in the fully folded
monoclinic form. These conserved intra- and intermolecular TPR-TPR interactions
are illustrative of a high-fidelity recognition mechanism. The two structures
also open up the possibility that partially folded forms of TPR may
be important in domain swapping and protein recognition.
See
more information about structure Link to Protein Database: http://www.rcsb.org/pdb/ |
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Octaheme Tetrathionate Reductase (OTR) OTR is a respiratory protein from the bacterium Shewanella oneidensis
that supports anaerobic respiration with tetrathionate and other sulfur
compounds as electron acceptors. The protein has eight covalently bound
heme groups, one of which has unprecedented ligation of the iron by
a lysine side chain, even though the heme is attached via a typical
CxxCH motif, where the histidine is a ligand in all other known c-type
cytochromes. This heme (heme II) binds ligands and is at the catalytic
centre of OTR.
Link to Protein Database: http://www.rcsb.org/pdb/
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