Luigi Grassi

11 Questions 63 Answers 0 Followers

Questions related from Luigi Grassi

pH depence of pyroglutamate formation from Gln different tahn from Glu?

The degradation pathways leading to Asn degradation are quite different from those of Asp (e.g. Asn is hydrolised at pH 1-4, is stable between pH 4-5 and undergoes general buffer catalised Asu...

20 November 2018 1,952 0 View

Can someone help me with diethylamine induced peptide degradation?

DEA treatment of an Fmoc protected peptide in solution caused degradation of the material as detected by analytical HPLC...has anybody any clue about what could be ever going on? Thank you for...

09 May 2015 1,200 3 View

Can a pyroglutamate moiety form within the peptide chain or has the occurrence of such PTM only been found at the N terminus?

literature references would be highly appreciated...thanks for the collaboration

19 March 2015 9,228 4 View

Why does resin turn to dark orange with Tetrakis (triphenylphosphine)palladium(0) ?

I am using the said reagent (0.5 eq) to cleave off the allyl Pg on resin, in presence of phenylsilane (25 eq) in DCM. After repeating the protocol 6 times for 20 min, the resin changed color,...

17 January 2015 5,239 7 View

Are dimethylacetals derived from aromatic aldehydes stable?

I am attempting to convert the salicylaldehyde into the correspondent dimethyl acetal using the following procedure. I dissolve it in MeOH in presence of triethyl orthoformate and decaborane as...

02 December 2014 921 6 View

What are the conditions for the conversion of the amino group in L cysteine into SH?

I would go for converting the NH into N2 then reaction with some source of SH...has anybody better ideas? (do not have the chance to use H2S)

04 November 2014 9,337 8 View

Would this treatment cause the unwanted deprotection of alkyl OH on the threonine from the Boc?

As a byproduct of my synthesis I might have a N,O Boc protected Thr, on resin, which for the next steps needs to be kept capped.The resin is subjected to a 6h treatment with 70% Pip in DMF, to...

19 September 2014 368 1 View

Where can I find salicylaldehyde UV spectra?

Could someone please give me any reference where I can find the UV spectra of salicylaldehyde? What influences would have the esterification of OH with a glycine lysine, on the UV/VIS behaviour?...

24 July 2014 703 3 View

Would a phenyl ester withstand repetitive FMOC removal cycles performed with DBU/HOBT 80mM/74mM?

Each cycle would be done with 2 treatments, 1 min each. Topic is phenyl esters hydrolysis.

08 July 2014 4,138 4 View

What is the best protocol for Oxazolidine synthesis on resin?

I am trying to couple the salicyl aldehyde to a Merrifield attached Thr, naturally after the tbu and Fmoc deprotection (performed with 80/10/10 TFA TIPS DCM, and piperidine, respectively). After...

27 June 2014 5,452 8 View

Does anyone have tips for the synthesis of a peptide C terminal Salicyl aldehyde?

I tried to make the reaction with DCC DMAP or DCC/HOBT between a protected peptide with the protected Salicyl aldehyde (as dimethyl acetal). The first time it came more or less good, then when I...

06 May 2014 8,817 2 View