Conformational flexibility in the catalytic triad revealed by the high-resolution crystal structure of Streptomyces erythraeus trypsin in an unliganded state

With more than 500 crystal structures determined, serine proteases make up greater than one‐third of all proteases structurally examined to date, making them among the best biochemically and structurally characterized enzymes. Despite the numerous crystallographic and biochemical studies of trypsin...

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Bibliographic Details
Published in:Acta crystallographica. Section D, Biological crystallography. Biological crystallography., 2014-03, Vol.70 (3), p.833-840
Main Authors: Blankenship, Elise, Vukoti, Krishna, Miyagi, Masaru, Lodowski, David T.
Format: Article
Language:English
Subjects:
apoenzyme
Biocatalysis
catalytic triad
Crystal structure
Crystallization
Crystallography, X-Ray
Ligands
Proteases
Protein Conformation
Protein Stability
Research Papers
Saccharopolyspora - enzymology
Serine Endopeptidases - chemistry
serine proteases
trypsin
Trypsin - chemistry
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Summary:With more than 500 crystal structures determined, serine proteases make up greater than one‐third of all proteases structurally examined to date, making them among the best biochemically and structurally characterized enzymes. Despite the numerous crystallographic and biochemical studies of trypsin and related serine proteases, there are still considerable shortcomings in the understanding of their catalytic mechanism. Streptomyces erythraeus trypsin (SET) does not exhibit autolysis and crystallizes readily at physiological pH; hence, it is well suited for structural studies aimed at extending the understanding of the catalytic mechanism of serine proteases. While X‐ray crystallographic structures of this enzyme have been reported, no coordinates have ever been made available in the Protein Data Bank. Based on this, and observations on the extreme stability and unique properties of this particular trypsin, it was decided to crystallize it and determine its structure. Here, the first sub‐angstrom resolution structure of an unmodified, unliganded trypsin crystallized at physiological pH is reported. Detailed structural analysis reveals the geometry and structural rigidity of the catalytic triad in the unoccupied active site and comparison to related serine proteases provides a context for interpretation of biochemical studies of catalytic mechanism and activity.
ISSN:1399-0047
0907-4449
1399-0047
DOI:10.1107/S1399004713033658