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PDBsum entry 1w3y
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References listed in PDB file
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Key reference
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Title
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L-Ascorbic acid 6-Hexadecanoate, A potent hyaluronidase inhibitor. X-Ray structure and molecular modeling of enzyme-Inhibitor complexes.
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Authors
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A.Botzki,
D.J.Rigden,
S.Braun,
M.Nukui,
S.Salmen,
J.Hoechstetter,
G.Bernhardt,
S.Dove,
M.J.Jedrzejas,
A.Buschauer.
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Ref.
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J Biol Chem, 2004,
279,
45990-45997.
[DOI no: ]
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PubMed id
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Abstract
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Hyaluronidases are enzymes that degrade hyaluronan, an important component of
the extracellular matrix. The mammalian hyaluronidases are considered to be
involved in many (patho)physiological processes like fertilization, tumor
growth, and metastasis. Bacterial hyaluronidases, also termed hyaluronate
lyases, contribute to the spreading of microorganisms in tissues. Such roles for
hyaluronidases suggest that inhibitors could be useful pharmacological tools.
Potent and selective inhibitors are not known to date, although L-ascorbic acid
has been reported to be a weak inhibitor of Streptococcus pneumoniae hyaluronate
lyase (SpnHL). The x-ray structure of SpnHL complexed with L-ascorbic acid has
been elucidated suggesting that additional hydrophobic interactions might
increase inhibitory activity. Here we show that L-ascorbic acid 6-hexadecanoate
(Vcpal) is a potent inhibitor of both streptococcal and bovine testicular
hyaluronidase (BTH). Vcpal showed strong inhibition of Streptococcus agalactiae
hyaluronate lyase with an IC(50) of 4 microM and weaker inhibition of SpnHL and
BTH with IC(50) values of 100 and 56 microM, respectively. To date, Vcpal has
proved to be one of the most potent inhibitors of hyaluronidase. We also
determined the x-ray structure of the SpnHL-Vcpal complex and confirmed the
hypothesis that additional hydrophobic interactions with Phe-343, His-399, and
Thr-400 in the active site led to increased inhibition. A homology structural
model of BTH was also generated to suggest binding modes of Vcpal to this
hyaluronidase. The long alkyl chain seemed to interact with an extended,
hydrophobic channel formed by mostly conserved amino acids Ala-84, Leu-91,
Tyr-93, Tyr-220, and Leu-344 in BTH.
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Figure 1.
FIG. 1. Chemical structures of L-ascorbic acid and
L-ascorbic acid 6-hexadecanoate.
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Figure 3.
FIG. 3. A, the SpnHL binding site for L-ascorbic acid
6-hexadecanoate. Hydrogen bonds are represented as dotted lines.
Shown is the final sigmaA-weighted  omit
map electron density calculated to a resolution of 1.65 Å
when the inhibitor was excluded from the model and contoured at
2.0  . B, schematic diagram
of interactions of L-ascorbic acid 6-hexadecanoate with SpnHL.
Hydrogen bonds are represented as dotted lines. Other residues
shown form hydrophobic interactions with the inhibitor. The
figure was made with LIGPLOT (35). C, binding mode of
hexasaccharide substrate. The coordinates of the hexasaccharide
substrate originate from its complex with SpnHL (Protein Data
Bank code 1loh [PDB]
(54)). D, binding mode of L-ascorbic acid 6-hexadecanoate. The
cryoprotectant xylitol molecule close to the inhibitor (see
text) is also shown (bottom right corner).
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2004,
279,
45990-45997)
copyright 2004.
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