Peptide guanidines

Didemnum rodriguesi from New Caledonia contained the unusual peptidyl alkaloid caledonin (76), that formed a complex with Zn2+ and Cu+ ions between thiol and primary amine groups [100], The minalemines D-F (77-79) are peptide guanidine derivatives isolated from a Caribbean collection of D. rodriguesi and contain a sulfamic acid group [101]. The stereochemistry of cyclodidemniserinol trisulfate (80) from a Palauan specimen of Didemnum guttatum was partially determined [102]. 

The peptide guanidine derivatives minalemines D-F (459-461), isolated from the New Caledonian tunicate Didemnum rodriguesi, were the first marine metabolites containing a sulfamic acid functional group [354]. Their structures were elucidated through their spectral data and by chemical transformations. 

Figure 23. Selected structures of amino acid and peptide guanidine alakloids compounds 168-184.

Exposito, M. A., Lopez, B., Fernandez, R., Vasquez, M. J., Debitus, C., Iglesias, T., Jimenez, C., Quinoa, E., Riguera, R., (1998). Minalemines A-F sulfamic acid peptide guanidine derivatives isolated finm the marine tunicate Didemnun rodriguesi. Tetrahedron 54,7539-7550. 

This Fmoc analog is prepared from the chloroformate, O-succinimide, or p-nitrophenyl carbonate and is cleaved with 10% piperidine in 1 1 6M guanidine/IPA. It was designed to interact strongly on a column of porous graphitized carbon so as to aid in the purification of peptides after cleavage from the resin. 

SnCl4, AcOH, THF, CH2CI2, toluene or CH3CN, 82-98% yield. This method was developed because acid-based methods were incompatible with the presence of a thioamide peptide bond. Guanidines were cleanly deprotected. ... 

Zhong HM, Greco MN, MaryanofF BE. Solid-phase synthesis of arginine-containing peptides by guanidine attachment to a sulfonyl linker. J Org Chem 1997 62 9326-9330. 

Dissolve a disulfide-containing protein or peptide at a concentration of l-10mg/ml in 6M guanidine hydrochloride, 0.01 M sodium phosphate, 0.15 M NaCl, pH 7.4. Alternative... 

Apply to the column 1.0ml of peptide solution (dissolved in equilibration buffer) to be reduced. Normally, small peptides (molecular weight less than or equal to that of insulin) require no deforming agent (denaturant) such as guanidine to be completely reduced. 

Brancia, F.L., Oliver, S.G., and Gaskell, S.J. (2000) Improved matrix-assisted laser desorption/ionization mass spectrometric analysis of tryptic hydrolysates of proteins following guanidination of lysine-containing peptides. Rapid Comm. Mass Spectrom. 14, 2070-2073. 

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