modification of PCR buffers - When and how (Aug/10/2007 )

hello just want to ask, how do we know when to modify the buffers used in PCR to increase its sensitiveness and how to know what other buffers or chemicals used to replace the existing ones. I only know buffers like TRIS buffers but i do not understand what its purpose and functions as... Is there a way to know what chemicals used, the reason of using, and how it works from a book or journal. My lecturers seems to know everything but he just would not explain how he know thier functions. Please help here. thank you....

well for the role of compounds in buffer, and thus, clues about what do buffer, there is an interesting topic here (ok i made it but still think it's interesting )

you may change PCR buffer when you se this in not to specific. So increasing DMSO is the principal technique i know. Little amount decrease the background. Honnestly i know it's decreasing the second structure DNA can form but for the rest, i don't really really know. you may also reduce original template too...
When youhave difficult templates, PCR, manuals of polymerases (Taq, triple master, pfu, phusion for examples) suggest you to play with MgCl2 concentration. this is assays you need to do. an other time, it's quite the experience.
I saw a nice collection names
you have to read protocols in :
www.protocol-online.org
www.biowww.net
website of current protocols