User:Michael Roberts/BIOL115 Chymo: Difference between revisions
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<StructureSection load='1afq' size='500' side='right' caption='Structure of Chymotrypsin (PDB entry [[1afq]])' scene='User:Michael_Roberts/BIOL115_Chymo/Start/1'> | <StructureSection load='1afq' size='500' side='right' caption='Structure of Chymotrypsin (PDB entry [[1afq]])' scene='User:Michael_Roberts/BIOL115_Chymo/Start/1'> | ||
== | == Tertiary structure == | ||
Chymotrypsin is initially synthesized as a 245 amino acid inactive precursor (a zymogen) termed chymotrypsinogen. Activation of chymotrypsinogen involves proteolytic cleavage at two sites along the chain and removal of two amino acids at each cleavage site. The resultant <scene name='User:Michael_Roberts/BIOL115_Chymo/Chains/1'>three chains</scene> are shown here (chain 1 = 1-13 in green; chain 2 = 16-146 in red; chain 3 = 149-24 in blue). Note, some amino acids at the temini of these chains are not shown in this representation (e.g. 11-13, 149, ). This is because these residues show too much flexibility in the crystal structures to give X-ray diffraction patterns which would locate them in space. | |||
The three chains are held together by five <scene name='User:Michael_Roberts/BIOL115_Chymo/Chains/2'>disulfide bonds</scene>. Can you identify the specific cys residues linked in each disulfide bond? Why do you think is it very difficult to obtain active chymotrypsin after denaturation and renaturation? | |||