Hello, can someone explain to me why does a small peptide (Sequence: STLHLVLRLRGG; MM: 1320,8 g/mol; Isoelectric point: pH 12,1; Net charge at pH 7: 2,1) that is soluble in water, heavily precipitates in contact with bacterial culture medium supplemented with 0.5% of albumin (without albumin there is no precipitation, but albumin is required for the bacterial growth). A LC-MS of this insoluble precipitate showed that it is composed of the peptide and albumin, which could only be dissolved with acetic acid. Can someone help me to understand what is happening here? Thanks so much!
Dear Tania Silva "Have A Happy Year - 2020"
This due to Negative Charge of 585 Amino acid Albumin - Charging your STLHLVLRLRGG peptide towards salt. This albumin was bigger in structure/molecular wise so easily give charge to small peptide even which favor to positive charge too.
So forming salt in aquas medium with albumin because of this salt you getting precipitation which was dissolving in Acid .
Albumin and your small peptide both are amino acid composite know, both are from Peptide-protein family, so easily getting interaction.
"All The Best For Your Research and Success"
Regards
Dr.R.Selva!
HI! I would guess peptide (polyelectrolyte)-induced albumin precipitation, either by destabilising the solvation sphere of albumin or by bridge formation and charge neutralization as the main mechanisms. ALBUMIN (when ionized in water at pH 7.4, as found in the body) is negatively charged and your peptide positively charged.
Please look at the following below links which may help you in your analysis:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5520048/pdf/ncomms16092.pdf
https://academic.oup.com/labmed/article/45/1/e25/2657886
Thanks
Dear Tania Silva "Have A Happy Year - 2020"
This due to Negative Charge of 585 Amino acid Albumin - Charging your STLHLVLRLRGG peptide towards salt. This albumin was bigger in structure/molecular wise so easily give charge to small peptide even which favor to positive charge too.
So forming salt in aquas medium with albumin because of this salt you getting precipitation which was dissolving in Acid .
Albumin and your small peptide both are amino acid composite know, both are from Peptide-protein family, so easily getting interaction.
"All The Best For Your Research and Success"
Regards
Dr.R.Selva!
Thank you to all the answers. I am just intrigued because I have worked with several small peptides with this culture medium supplemented with albumin, and this never happened. So, what is so special about this one that precipitates when in the presence of it? Also, th precipitate that is formed is not the "usual" white powder, but some kind of film in suspension. Thanks so much again!
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