[Bioperl-l] Existing bioperl module/function?

[Sun, Jian]

Dear all;
   I need some help on this problem: Is there any bioperl module or functions available to be used to get the corresponding nucletide sequence of a certain protein ? Then also can retrive the oligo sequence of a specified peptide segment of this protein sequence? 
 
   At the NCBI site, we can retrieve the both sequences through its protein and nucleotide database seperately and then find the corresponding matches at the certain sequence position. In bioperl, it is possible that I may can use the reverse translation to soluve this, but it leads to the degenerate sequence, not the one to one match of a certain protein.  And I am more interested in the retriving the corresponding nucleotide sequence of the peptide fragment of the same protein.  So I just wonder if there is a more direct way through using the existing bioperl module. 
 
Thanks in advance
Jian Sun