Chymotrypsin: Difference between revisions
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==Active site residues== | ==Active site residues== | ||
The active site of an enzyme is the location where the substrate binds and where the chemical reaction occurs. Active site residues are those amino acid residues demonstrated to have importance for catalysis or substrate binding. Chymotrypsin contains three residues, Ser 195, His 57 and Asp 102, which are known as its <scene name='Chymotrypsin/Chymotrypsin_triad/2'>catalytic triad</scene>. Similar three-dimensional arrangements of a serine, a histidine and an aspartate are observed in many other proteases, and the role of these three residues in catalysis has been studied extensively. Serine acts as a nucleophile (contributing the electron pair for a new bond) attacking the carbonyl carbon of the peptide bond to be hydrolyzed. Histidine and aspartate turn serine into a better nucleophile by assisting in removing a hydrogen ion from serine. | The active site of an enzyme is the location where the substrate binds and where the chemical reaction occurs. Active site residues are those amino acid residues demonstrated to have importance for catalysis or substrate binding. Chymotrypsin contains three residues, Ser 195, His 57 and Asp 102, which are known as its <scene name='Chymotrypsin/Chymotrypsin_triad/2'>catalytic triad</scene>. Similar three-dimensional arrangements of a serine, a histidine and an aspartate are observed in many other proteases, and the role of these three residues in catalysis has been studied extensively. Serine acts as a nucleophile (contributing the electron pair for a new bond) attacking the carbonyl carbon of the peptide bond to be hydrolyzed. Histidine and aspartate turn serine into a better nucleophile by assisting in removing a hydrogen ion from serine. | ||
==Further reading== | |||
You can learn more about chymotrypsin structure, function and regulation in this publicly available [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=stryer&part=A1170#A1171 chapter] of the Biochemistry textbook by Berg, Tymoczka and Stryer. | |||
Revision as of 20:41, 19 February 2010
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Please click on the green links as you read through the text.
OverviewOverview
Chymotrypsin is an enzyme catalyzing the hydrolysis of peptide bonds. While it occurs in many organisms, the most-studied chymotrypsin is that from cows (bovine chymotrypsin). In its mature form, bovine chymotrypsin is a protein consisting of 245 amino acids. This string of amino acids folds into a . (Can you guess where the substrate might bind? Try spinning around the molecule by dragging it with the mouse cursor. There should be a pocket somewhere on the surface of the enzyme). The path of the backbone is easier to see in this , which shows that chymotrypsin folds into two large beta sheets.
Active site residuesActive site residues
The active site of an enzyme is the location where the substrate binds and where the chemical reaction occurs. Active site residues are those amino acid residues demonstrated to have importance for catalysis or substrate binding. Chymotrypsin contains three residues, Ser 195, His 57 and Asp 102, which are known as its . Similar three-dimensional arrangements of a serine, a histidine and an aspartate are observed in many other proteases, and the role of these three residues in catalysis has been studied extensively. Serine acts as a nucleophile (contributing the electron pair for a new bond) attacking the carbonyl carbon of the peptide bond to be hydrolyzed. Histidine and aspartate turn serine into a better nucleophile by assisting in removing a hydrogen ion from serine.
Further readingFurther reading
You can learn more about chymotrypsin structure, function and regulation in this publicly available chapter of the Biochemistry textbook by Berg, Tymoczka and Stryer.