View source for 1sgc

[[Image:1sgc.gif|left|200px]]<br /><applet load="1sgc" size="350" color="white" frame="true" align="right" spinBox="true" 
caption="1sgc, resolution 1.8&Aring;" />
'''THE 1.8 ANGSTROMS STRUCTURE OF THE COMPLEX BETWEEN CHYMOSTATIN AND STREPTOMYCES GRISEUS PROTEASE A. A MODEL FOR SERINE PROTEASE CATALYTIC TETRAHEDRAL INTERMEDIATES'''<br />

==Overview==
The naturally occurring serine protease inhibitor, chymostatin, forms a hemiacetal adduct with the catalytic Ser195 residue of Streptomyces griseus protease A. Restrained parameter least-squares refinement of this complex to 1.8 A resolution has produced an R index of 0 X 123 for the 11,755 observed reflections. The refined distance of the carbonyl carbon atom of the aldehyde to O gamma of Ser195 is 1 X 62 A. Both the R and S configurations of the hemiacetal occur in equal populations, with the end result resembling the expected configuration for a covalent tetrahedral product intermediate of a true substrate. This study strengthens the concept that serine proteases stabilize a covalent, tetrahedrally co-ordinated species and elaborates those features of the enzyme responsible for this effect. We propose that a major driving force for the hydrolysis of peptide bonds by serine proteases is the non-planar distortion of the scissile bond by the enzyme, which thereby lowers the activation energy barrier to hydrolysis by eliminating the resonance stabilization energy of the peptide bond.

==About this Structure==
1SGC is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_chryseus Streptomyces chryseus] with <scene name='pdbligand=CST:'>CST</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SGC OCA]. 

==Reference==
The 1.8 A structure of the complex between chymostatin and Streptomyces griseus protease A. A model for serine protease catalytic tetrahedral intermediates., Delbaere LT, Brayer GD, J Mol Biol. 1985 May 5;183(1):89-103. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=3892018 3892018]
[[Category: Single protein]]
[[Category: Streptomyces chryseus]]
[[Category: Brayer, G D.]]
[[Category: Delbaere, L T.J.]]
[[Category: CST]]
[[Category: hydrolase (serine proteinase)]]

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