Analysis of proteins from milk

Dear All,

One of my undergraduate students has initiated some work to analyse
nutritional content of milk from some indigenous animals. One of the
experiments we intend to carry out is quantification and SDS-PAGE of milk
proteins. Can somebody out there advise on any available method that can
remove the "milk colour" which would probably interfere with our assay or
analysis?

Dr. D. O. Ogoyi
Department of Biochemistry
University of Nairobi
P. BOX 30197, 00100
NAIROBI, KENYA

[Only registered users see links. ] wrote:

It won't. "Milk colour" *is* protein! Milk is a colloid solution of
aggregated casein. If you insist in removing casein, you need
to lookup standard methods of making whey. I think adding
acetate and centrifuging should will work.

DK

Am 22.08.2007, 07:14 Uhr, schrieb <[Only registered users see links. ].ke>:


Nutritional value depends on the amino acid composition more han on the
number or nature of proteins, so hydrolysis followed by HPLC aa analysis
would probably give more information than SDS-PAGE. Hydrolysis can be
accomplished either by 6 N HCl (24 h, 110 deg C in evacuated and sealed
ampules), by barium hydroxide (McGrath 1972) or NaOH (Landry & Delhaye
1996). It is generally worthwhile to also submit samples with known
amounts of a standard protein to analysis, to get a feel for the error
associated with this procedure.

The "milk colour" is caused by fat droplets, so the standard
Chloroform/Methanol (Wessel & Flügge 1984) precipitation should do fine
for removing it.