DNA denaturing agents

[shankar]

Hi everybody,

What are the denaturing agents that can be used to denature a double
strand (e.g. Lambda DNA) to get a single strand, preserving
streptavidin-biotin bonds? Also what's the ideal pH and salt
concentration to keep the single strand intact after the double
stranded DNA was denatured?

Also,

What is the largest  commercially available Single Stranded DNA
(that's much longer than the M13 (7249 bp) DNA)


Looking forward to your replies.

Thanks in advance