1st strand buffer for cDNA synthesis - (Dec/12/2008 )

Hello,

The 5x first strand buffer for cDNA synthesis consists of: 250 mM Tris-HCl pH 8,3; 15 mM MgCl2 and 375 mM KCl.
Tris-HCl is in the buffer to control the pH. MgCl2 is in it because your reverse transcriptase needs Mg2+.
But why KCl is added? Are the K+ necessary to keep the DNA soluble or something like that?

Can anyone help me?

Thanks in advance.

BBBBUUUUUFFFFEEERRRRR.....like NaCl. KCl is the normal saline of PCR