Action Mechanism                                                        

    When the environment is rich in Trptophan, bacteria will switch Trp  

    Operon off due to the action of Trp repressor. The binding of two Trpto-  

    phan molecules per Trp repressor monomer as cofactors followed by the 

    conformational change on the Trp repressor bends one of the chains in

    the Trp repressor to certain angle that it readily insert into the minor 

    groove DNA and block transcription hereafter.   

ID:1PAR     
Authors:J.F.SCHILDBACH,M.E.MILLA,P.D.JEFFREY,B.E.RAUMANN,R.T.SAUER

resolution: 2.4A. 4 protein chains & 22-mer DNA(P8L)         
 

3'TATCATCTCACGAAGATAG TAA 5' (f chain)

               Hydrogen bonds:                                    

                     Gln9....A18  Distance=3.14A  color=red       

                     Asn11...C16  Distance=3.15A  color=blue       

                     Arg13...G8   Distance=2.67A  color=green     

               Commands:                                          

                     show sequence                         

                     select *a                            

                     ribbon on                            

                     color white                           

                     select gln9a, asn11a, arg13a                      

                     ball & stick on                         

                     select gln9a                           

                     color red                              

                     select asn11a                           

                     color blue                               

                     select arg13a                            

                     color green                              

                     select dna                               

                     backbone on                              

                     color white                              

                     select g8e, c16e, a18e                         

                     wireframe on                             

                     select a18f                              

                     color red                                

                     select c16f                               

                     color blue                               

                     select g8e                               

                     color green