Need help on peptide solubility and MIC test?

[foh_le]

i am doing some MIC test which require addition of peptides in it.

At first I have successfully dissolved the peptides in water or acetonitrile according to the manufacturer's guidelines. However, upon addition of these peptides into mueller-hinton broth (MHB) suspended with bacteria for MIC, I found that the peptides gave a turbid appearance to the crystal clear MHB especially the first well or second with high concentrations..

After incubation for 24hr, I noted that there were some precipitates formed at the bottom of 96well plate across the serial dilutions, begun with or without precipitate at the highest concentrations increasing down the lowest, It is not possibly due to bacterial clumps as observed under the microscope but merely some globular structures.

I hypothesized that the peptides might have been precipitated out or agglutinated or formation of any kinds that could have reduce its solubility in MHB, and if i am right, this will reduced give a false negative reading and will greatly affect the MIC of my test.

Any expert have such experiences before or anyone know what is the problems?

[glbiochem]

For cell research work, you'd better to dissolve the peptide with water directly.
If the peptide is too hydrophobic, please add 10-20ul DMSO at first.
After dissolve the peptide to clear, pls dilute the peptide with water to 900ul.
Then add 100ul 10*buffer(used in our MIC test) to the peptide solution.
Drop it into your reaction well and allocate another vacant well to watch whether there is precipitates.

Best Wish,

Mr. David Wei
Senior Sales Manager

GL Biochem(Shanghai) Ltd.
519 Ziyue Road, Minhang
Shanghai,200241
PR China

Mobile: 0086-15301650007(24 hour)
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2009-06-15
13:45:02