What smear bands mean?

[AK]

260/280 between 1.80-1.90 together with 260/230 around 2.0 indicates pure 
plasmid DNA.

260/280 > 2.0 = too much RNA in sample

260/280 < 1.8 = protein contamination

Regards,
AK


"Sudheendra Rao N R" <sudhee26 from gmail.com> wrote in message 
news:mailman.828.1204136067.2451.methods from net.bio.net...
> Hi,
> well, i know (i think i know :)) about the ratios
> 260/280: DNA purity (ideal more than 1.6)
> DNA max at 260 (i guess its because of Adenine)
> RNA max at 280 (??Uridine)
> 260/230: i guess organic solvents have absorption maxima at 230nm..like
> ethanol, phenol..isopropanol..
> whats this smear band???
>
> On Wed, Feb 27, 2008 at 5:17 AM, DK <dk from no.email.thankstospam.net> wrote:
>
>> In article <mailman.811.1204047972.2451.methods from net.bio.net>, TRAN HO
>> QUANG <quangtranho from yahoo.com> wrote:
>> >What smear bands mean for above and below main band of DNA and PCR
>> products?
>>
>> They mean other DNA molecules - although the smear above may
>> mean  using bad agarose and/or overloading the gel.
>>
>> > Which one corespondent for A260, A260/A280 or A230 ratio?
>>
>> All of them. Though I am not sure about 230 - I'd imagine it's
>> pretty useless regardless. (Someone please educate me if
>> that's not the case).
>>
>> DK
>>
>>
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>
>
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