collagen labelling - (Jun/23/2008 )

I've label to collagen with a fluorescent dye. My problem is that collagen is soluble around pH 3-4. But FITC, EITC etc are functional at pH 8 or above, & at that pH collagen precipitates.
Can anyone help me please.
Thanks.

Try more dliuted solutions of collagen, then concentrate afterwards, maybe. You need to keep NH2 groups in free base status and pH7.5-9 is needed for the reaction to occur.