@article {532,
	title = {Targeted, Site-specific quantitation of N- and O-glycopeptides using (18)O-labeling and product ion based mass spectrometry.},
	journal = {Glycoconj J},
	volume = {34},
	year = {2017},
	month = {2017 Feb},
	pages = {95-105},
	abstract = {<p>The site-specific quantitation of N- and O-glycosylation is vital to understanding the function(s) of different glycans expressed at a given site of a protein under physiological and disease conditions. Most commonly used precursor ion intensity based quantification method is less accurate and other labeled methods are expensive and require enrichment of glycopeptides. Here, we used glycopeptide product (y and Y0) ions and (18)O-labeling of C-terminal carboxyl group as a strategy to obtain quantitative information about fold-change and relative abundance of most of the glycoforms attached to the glycopeptides. As a proof of concept, the accuracy and robustness of this targeted, relative quantification LC-MS method was demonstrated using Rituximab. Furthermore, the N-glycopeptide quantification results were compared with a biosimilar of Rituximab and validated with quantitative data obtained from 2-AB-UHPLC-FL method. We further demonstrated the intensity fold-change and relative abundance of 46 unique N- and O-glycopeptides and aglycopeptides from innovator and biosimilar samples of Etanercept using both the normal-MS and product ion based quantitation. The results showed a very similar site-specific expression of N- and O-glycopeptides between the samples but with subtle differences. Interestingly, we have also been able to quantify macro-heterogeneity of all N- and O-glycopetides of Etanercept. In addition to applications in biotherapeutics, the developed method can also be used for site-specific quantitation of N- and O-glycopeptides and aglycopeptides of glycoproteins with known glycosylation pattern.</p>
},
	issn = {1573-4986},
	doi = {10.1007/s10719-016-9733-8},
	author = {Srikanth, Jandhyam and Agalyadevi, Rathinasamy and Babu, Ponnusamy}
}
@article {509,
	title = {Structure of a heterogeneous, glycosylated, lipid-bound, in vivo-grown protein crystal at atomic resolution from the viviparous cockroach Diploptera punctata. [Mass spectrometry - Glycomics]},
	journal = {IUCrJ},
	volume = {3},
	year = {2016},
	month = {2016 Jul 01},
	pages = {282-93},
	abstract = {<p class="rtejustify">Macromolecular crystals for X-ray diffraction studies are typically grown in vitro from pure and homogeneous samples; however, there are examples of protein crystals that have been identified in vivo. Recent developments in micro-crystallography techniques and the advent of X-ray free-electron lasers have allowed the determination of several protein structures from crystals grown in cellulo. Here, an atomic resolution (1.2 {\r A}) crystal structure is reported of heterogeneous milk proteins grown inside a living organism in their functional niche. These in vivo-grown crystals were isolated from the midgut of an embryo within the only known viviparous cockroach, Diploptera punctata. The milk proteins crystallized in space group P1, and a structure was determined by anomalous dispersion from the native S atoms. The data revealed glycosylated proteins that adopt a lipocalin fold, bind lipids and organize to form a tightly packed crystalline lattice. A single crystal is estimated to contain more than three times the energy of an equivalent mass of dairy milk. This unique storage form of nourishment for developing embryos allows access to a constant supply of complete nutrients. Notably, the crystalline cockroach-milk proteins are highly heterogeneous with respect to amino-acid sequence, glycosylation and bound fatty-acid composition. These data present a unique example of protein heterogeneity within a single in vivo-grown crystal of a natural protein in its native environment at atomic resolution.</p>
},
	doi = {10.1107/S2052252516008903},
	author = {Banerjee, Sanchari and Coussens, Nathan P and Gallat, Fran{\c c}ois-Xavier and Sathyanarayanan, Nitish and Srikanth, Jandhyam and Yagi, Koichiro J and Gray, James S S and Tobe, Stephen S and Stay, Barbara and Chavas, Leonard M G and Ramaswamy, Subramanian}
}
