Nanodrop - (Jun/25/2008 )
Is anyone using nanodrop for measuring protein concentration? I am just wondering whether you get a peak at 220-230 nm in addition to the 280 peak? What is the large 220 nm peak?
Absorbance by Peptide bond...buffers(Tris) and even Oxygen..Peptide bond absorbs maximum at 220 nm.
we use bradford method for the quantitation of protein. you know that this is very cheap and best.
but you can use a wavelength of 220 nm if you want to read peptide bonds.
and also, you can see the book of manufacturer of the nanodrop (http://chroma.med.miami.edu/arrays/downloads/nd-1000-users-manual.pdf). maybe it take more information of your problem.
My dna extraction protocol used to carry a lot of salts into the final DNA dolution, this caused my 230 to boost up. Isothiocyanates and phenols (actually any cyclic slvent) also absorb at aroudn 230 nm. Best.