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Encyclopedia > Subtilisin
Subtilisin

Crystal structure of Subtilisin
Gene code:
Structure:
Recent publications:
protein type: Serine protease
Functions:
Domains:
Diseases:

Subtilisin (serine endopeptidase) is a proteolytic enzyme initially obtained from Bacillus subtilis. It is secreted in large amounts from many Bacillus species. Image File history File links This is a lossless scalable vector image. ... Image File history File links No higher resolution available. ... X-ray crystallography, also known as single-crystal X-ray diffraction, is the oldest and most common crystallographic method for determining the structure of molecules. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Crystal structure of Trypsin, a typical serine protease. ... This article is about the medical term. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Binomial name Bacillus subtilis (Ehrenberg 1835) Cohn 1872 Gram-stained Bacillus subtilis Sporulating Bacillus subtilis Bacillus subtilis is a Gram-positive, catalase-positive bacterium commonly found in soil. ...


The structure of subtilisin has been determined by X-ray crystallography. It is a 275 residue globular protein with several alpha-helices, and a large beta-sheet. It is structurally unrelated to the chymotrypsin-clan of serine proteases, but uses the same type of catalytic triad in the active site. This makes it the classic example of convergent evolution. X-ray crystallography, also known as single-crystal X-ray diffraction, is the oldest and most common crystallographic method for determining the structure of molecules. ... A residue, broadly, is anything left behind by a reaction or event. ... 3-dimensional structure of hemoglobin, a globular protein. ... Side view of an α-helix of alanine residues in atomic detail. ... Diagram of β-pleated sheet with H-bonding between protein strands The β sheet (also β-pleated sheet) is the second form of regular secondary structure in proteins — the first is the alpha helix — consisting of beta strands connected laterally by three or more hydrogen bonds, forming a generally twisted, pleated sheet. ... Chymotrypsin (bovine γ chymotrypsin: PDB 1AB9, EC 3. ... Three amino acid residues found inside the active site of certain proteases. ... The active site of an enzyme is the binding site where catalysis occurs. ... In evolutionary biology, convergent evolution is the process whereby organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches. ...


Charge-relay Site of Subtilisin

The active site features a charge-relay network involving Asp-32, His-64, and active site Ser-221 arranged in a catalytic triad. The charge-relay network functions as follows: The carboxylate side chain of Asp-32 hydrogen bonds to a nitrogen-bonded proton on His-64's imidazole ring. This is possible because Asp is negatively charged at physiological pH. The other nitrogen on His-64 hydrogen bonds to the O-H proton of Ser-221. This last interaction results in charge-separation of O-H, with the oxygen atom being more nucleophilic. This allows the oxygen atom of Ser-221 to attack incoming substrates (ie. peptide bonds), assisted by a neighboring carboxyamide side chain of Asn-155. Imidazole is a heterocyclic aromatic organic compound. ... For other uses, see PH (disambiguation). ...


Even though Asp-32, His-64, and Ser-221 are sequentially far apart, they converge in the 3D structure to form the active site. In biochemistry, the tertiary structure of a protein is its overall shape. ...


To summarize the interactions described above, Ser-221 acts as a nucleophile and cleaves peptide bonds with its partially negative oxygen atom. This is possible due to the nature of the charge-relay site of subtilisin. In chemistry, a nucleophile (literally nucleus lover) is a reagent which is attracted to centres of positive charge. ... A peptide bond is a chemical bond that is formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O). ...


References

Deber, C.M. (Lecturer). (2006, Sep. 29). BCH210H1F. [Lecture]. Toronto: University of Toronto.:)


  Results from FactBites:
 
Title of Invention: Multiply mutated subtilisins (12227 words)
Subtilisin DY comprises 274 amino acids and differs from subtilisin Carlsberg in 32 amino acid positions and from subtilisin BPN' by 82 amino acid replacements and one deletion (subtilisin DY lacks an amino acid residue corresponding to residue 56 of subtilisin BPN').
Subtilisins that may be modified in accordance with the present invention include, but are not limited to, naturally occurring subtilisins represented by the amino acid sequence of subtilisin Carlsberg, subtilisin BPN' the aprA gene product of Bacillus subtilis, subtilisin DY and the subtilisin of Bacillus mesentericus, and the subtilisin of B. subtilis var.
Heat denaturation is an irreversible reaction for subtilisin: in the absence of protease inhibitor the intact enzyme digests the unfolded form, in the presence of inhibitor the protein precipitates as it unfolds.
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