Glycopeptide chemical characterization

Clark, R.S., Banerjee, S., and Coward, J.K. (1990) Yeast oligosaccharyltrans-ferase glycosylation of peptide substrates and chemical characterization of the glycopeptide product./. Org. Chem. 55, 6275-6285. 

Goussault, Y., and Bourrillon, R., 1970, Chemical characterization of two urinary sialic acid-rich glycopeptides, Biochem. Biophys. Res. Commun. 40 1404. 

The development glycopeptide libraries obtained by the split-mix method is severely hampered by the lack of concurrent development of a general, facile separation and characterization technology. Some headway has been made with chemical coding of the libraries, but very few direct methods of analysis exist. One promising method that could be applied to the direct characterization of both types of libraries is mass spectrometry. More specifically, post-source-decay matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (PSD-MALDI-TOF-MS) and CID-FAB/MS/MS have been used to characterize glycopeptides.53-55... 

Fig. 25 Characterization and luciferase expression of PGP DNA condensates in vivo. These results show that luciferase expression is dependent on galactose incorporation but independent of amount of melittin. (a) Represents the input mol ratio of Cys-terminated melittin, PEG-peptide, and glycopeptide. (b) Represents the measured mol ratio of Cys-terminated melittin, PEG-peptide, and glycopeptide for each purified PGP. (c) Values are the calculated MW based on polylysine standards, (d) Values are the calculated MW based on PEG standards, (e) The mean particle size determined at a stoichiometry of 0.3 nmol of PGP per mg of DNA. The value represents the mean diameter (nm) based on unimodal analysis, (f) The zeta potential of PGP DNA condensates at a stoichiometry of 0.3 nmol of PGP per mg of DNA. (g) The metabolic half-life of PGP 125I-DNA in triplicate mice. The results are derived from Fig. 6. (h) The PC/NPC ratio of DNA-targeted liver, (i) Represents a control PGP 3 in which galactose has been removed. Figure adapted with permission from [182], 2007 American Chemical Society...

Subsequent experimental work in this laboratory was aimed at the systematic development of an efficient method for isolating the proteinaceous surfactants, which help stabilize natural microbubbles, from both commercial agarose powder and from forest soil samples collected locally. Successful isolation of this glycopeptide fraction was eventually achieved (ref. 322), and the results obtained from an extended program of chemical analysis, to further characterize and compare chemically these proteinaceous surfactants from both natural substances, are described below. 

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