41 Questions 51 Answers 0 Followers
Questions related from Antonio Rosato
Hi to all, I'm experiencing a too weird fact. I was studying how the matrix of my sample affected ylthe instrumental response of my analyte in LC MS. I use an esi detector, a c18 column. My...
27 April 2023 6,650 3 View
hi to all, i know that it could be a stupid question. I am analysing by means of mass spectrometry a molecule having various O- moieties. interestingly, in ESI- I observe both MH- but also a 22 Da...
29 September 2021 1,987 4 View
I have always known that differently from ESI, the APCI source produces the molecular ion, because the formation of ions depends on the glow discharge, differently from the ESI source, where the...
14 September 2021 6,580 2 View
Hi to all, I'm exeriencing some issues with my quantification standard I use to evaluate peaks eluted at hplc and analysed in ESI MS positive ion mode. In particular, I observe a time-dependent...
04 July 2018 3,521 3 View
Hi to all, frequently i need to analyse by LC-MS samples containing polysorbate. consequently, i experience high background in the other analysis, and the next analysis are interfered by the...
15 September 2017 7,693 2 View
hi to all, i have a stock solution of an ab amyloid peptide previously treated according to the standard protocols. this solution has been stocked at -20°C for a couple of years, and the peptide...
26 September 2016 5,664 3 View
hi to all, i would like to estimate the superficial pH on spherical particles having dimension of nanometers. since the surface is regular and omogeneusly coated, i was wandering if could i infere...
22 March 2016 2,088 2 View
hi to all, I need to use amicon ultra filtration devices at low Temperatures in order to purify a protein sensitive to this parameter. can i use amicon devices in a centrifugue refrigerated at 4°C?
18 March 2016 7,508 3 View
what does it mean if the OD600 of an E.Coli Culture decreases?
15 February 2016 2,680 5 View
hi to all, i was wandering if it is possible to transform bl21 de3 cells with two plasmids. the aim is to espress 2 proteins at once. the two plasmids are both iptg inducible, and ampicillin...
08 February 2016 1,598 7 View
hi to all, i have noticed that if i incubate two parallel bacterial cultures in the same conditions ( one where i add IPTG for protein induction and another in which I don't add anything) the OD...
29 January 2016 2,209 6 View
If I add chloramphenicol only in the overnight liquid culture, is ok? should the chloramphenicol be present also during the induction of the protein? thank you
26 January 2016 7,067 3 View
hi to all, I'm trying to express a protein in E.coli bl21DE3 gold. this protein is about 70 aa long and is very similar to a metallothionein, having 6 cysteines. the plasmid is optimized for the...
18 December 2015 4,168 10 View
Hi to all, I need to incubate a plate of hela cells in a solution of PBS (without Mg and Ca). Is it dangerous? do PBS cause detachment or morphology changes of the cells if I incubate them for 30...
24 November 2015 1,194 3 View
hi to all, I'm studying a protein having 3 cysteines. When I perform the reaction with IAM, I notice that the protein is being Carbamidomethylated on four residues. are there other residues in...
19 November 2015 1,683 3 View
Hi to all, I'm wondering if glucose polymers such cyclodextrins, glycogen and more complex polymers, are metabolized by E.Coli. Thank you
21 October 2015 2,804 3 View
Hi to all, I'm trying to express and purify a protein. Once the lysate was obtained, I performed an ion exchange chromatography followed by a size exclusion. In the chromatogram of the SEC, i have...
25 May 2015 6,765 8 View
Hi to all, I'm trying to study a protein DNA complex. when I try EMSA i have positive results with the nuclear extracts, while with the recombinant protein I have never seen any interaction. On...
28 March 2015 10,030 5 View
Hi to all, I have prepared a protein complex made from two monomers keep together by a metal, I'd like to analyse it by reverse phase HPLC using a gradient from 2% of ACN, to 100%. i have some...
13 March 2015 8,205 6 View
Hi to all, I need to analyse by mass spec. (ESI-MS) a pool of proteins Eluted with the Glycine HCl buffer at pH 2. I was wandering if this buffer is suitable for mass spec. analysis since Cl- ions...
11 March 2015 3,111 8 View
Hi to all, I performed a pull down assay of a protein using streptavidin beads attached to a biotinylated oligonucleotide probe, and once the elution step and the boiling step (in loading buffer...
09 March 2015 2,893 8 View
Hi to all, I have performed several experiments to study the interaction between a protein and a DNA strand supposed to be its binding site. I've studied this interaction with the recombinant...
07 March 2015 3,608 10 View
Hi to all, I'm trying to characterize the alleged interaction between a protein and liposomes having a specific ratio of anionic ang zwitterionic phospholipids. I have performed both a control run...
07 March 2015 1,694 3 View
Hi to all, I have to perform a trypsin in-solution digestion of a protein sample. I would like to avoid the use of SDS/Urea/GnCl. Is possible to perform the trypsin digestion of my proteing...
27 February 2015 8,224 10 View
Hi to all, I have to perform an experiment in order to evaluate the behaviour of a protein as the dielectric constant of the bulk varies. So I thought to study the extrinsic fluorescence of the...
23 February 2015 1,890 2 View
Hi to all, I'm approaching to the haddock web-tool for the first time. I got the username and password for the easy interface. I'd like to know wheather i'm on the right way. Once I've uploaded...
31 December 2014 5,609 11 View
Hi to all, If a protein is encapsulated in a liposome, does it respond to colorimetric methods such the Bradford assay? Or if I perform an electrophoresis, does the protein respond to silver...
25 November 2014 2,193 3 View
hi to all, I am currently dealing with a cysteine rich protein having a cysteine metal binding domain cxxc and another cysteine rich motif that could be a heavy metal binding domain CxxxCxxCxC....
15 September 2014 3,478 3 View
Hi to all. I do not have an ESI-MS coupled to an hplc, and I need to analyze a band excised from a gel. Once I have desalted the tryptic digest, how can I set the database search considering that...
05 September 2014 5,489 7 View
Hi to all, I'd like to know if is possible to excise a band from a mono dimensional protein electrophoretic gel, perform a classical in-gel digestion, and then analyze it with ESI-MS by a direct...
05 September 2014 3,576 10 View
Hi to all, I'd like to know how to perform a search in the MASCOT search engine against a whole 15 N fully labelled protein. Thank You
28 July 2014 5,137 0 View
Hi to all, I'd like to know if it would be possible that some amino acid modifications occur chemically during protein sample preparation or during the mass spectra acquisition. For example is it...
24 July 2014 9,864 6 View
Hi to all, The cross linking step in the EMSA assay is performed to covalently bind the DNA probe to the positively charged membrane. Does the protein DNA interaction turn covalent too due to...
20 July 2014 5,282 1 View
Hi to all, I'd like to know if ESI-q-ToF allows the quantification of proteins in the femtogram range. Thank you
20 July 2014 1,398 8 View
Hi to all, I'd like to perform an immunoblotting against a protein on my EMSA. I would like to know if I can strip the streptavidin-HRP / biotinylated DNA probe complex from the membrane and...
07 July 2014 7,343 2 View
I performed some EMSA assays with very puzzling results. Although I'm sure that in the shifts there is my protein, I'd like to better characterize them. Is it possible to excise the band of...
29 June 2014 8,694 2 View
I'm wondering whether an interaction between copper I ions and DNA is possible and to what extend this interaction could affect the DNA conformation. Do you know any literature talking about this...
31 May 2014 3,777 3 View
I'm planning to do a 15N-1H HSQC experiment to verify the formation of an alleged DNA-Protein complex. I've found a protocol in which the concentration of the salts in the buffer are roughly of...
23 April 2014 8,161 7 View
I have to perform an NMR experiment on a sample to study the hypothetical formation of a protein-DNA complex. The switch from a high salt concentration buffer is needed (in which there is the...
23 April 2014 2,850 2 View
The role of ionic force on the protein-DNA complex's formation is well known. There are some EMSA protocols in which the binding buffer is prepared with NaCl and KCl, others in which there is...
05 March 2014 6,924 0 View
I have the suspect that a transcription factor interacts as a dimer with the DNA and my wish is to characterize it. I'm wondering if it was possible to extract the protein nuclear fraction of...
18 February 2014 5,217 3 View
