Charge derivatization

Recently, a charge derivatization method was applied (Lee et al., 2004) to successfully analyze small amine molecules in buffer. The compounds to be analyzed were primary and secondary amines including several antibiotics. The amines were mixed with a 10-fold excess of A-hydroxysuccinimidc ester. Although the reaction mixture contained millimolar concentrations of buffer, the mixture was directly analyzed without a desalting step. While noteworthy, this technique adds another tedious step to the analysis, and linearity was limited to a single order of magnitude. 

Lee, P. J., Chen, W., and Gebler, J. C. (2004). Qualitative and quantitative analysis of small amine molecules by MALDI-TOF mass spectrometry through charge derivatization. Anal. Chem. 76 4888-4893. 

L. A. Gennaro, D. J. Harvey, and P. Vouros, Reversed-phase ion-pairing liquid chromatog-raphy/ion trap mass spectrometry for the analysis of negatively charged, derivatized glycans, Rapid Common. Mass Spectrom., 17 (2003) 1528-1534. 

N. Sadagopan, M. Malone, J.T. Watson, Effect of charge derivatization in the determination of phosphorylation sites in peptides by ESI-CID-AIS—AIS, J. Mass Spectrom., 34 (1999) 1279. 

Nishiyama et al. (2004) set out to quantitate DHT in human serum and prostate biopsy tissue using LC-MS with charged derivatization to the A-methylpyridinium derivative. Prostate tissue DHT was dissolved in alkaline solution, extracted by SPE and derivatized before LC-MS analysis [ESI, positive ion mode, selected reaction monitoring (SRM)]. Pretreatment values in patients with N = 69) or without N = 34) prostate cancer were, for serum DHT, 423.9 pg mL ( 1.46 nmol L ) with SD 243.2 pg mL (< 0.84 nmol L ) or... 

Higashi, T, Yamauchi, A., Shimada, K., Koh, E., Mizokami, A. and Namiki, M. (2005). Determination of prostatic androgens in 10 mg of tissue using Uquid chromatography-tandem mass spectrometry with charged derivatization. Anal. Bioanal. Chem., 382, 1035-1043. 

SCHEME 4.2 Fixed-charge derivatization and selective gas-phase fragmentation of methionine fixed-charge sulfonium ion derivatized peptides. (Reproduced from Amunugama, M. Roberts, K.D. Reid, G.E., J. Am. Soc. Mass Spectrom. 2006,17,1631-1642. With permission from the American Society for Mass Spectrometry, published by Elsevier Inc.)... 

Adamczyk, M. Gebler, J.C. Wu, J. Charge derivatization of peptides to simplify their sequencing with an ion trap mass spectrometer. Rapid Commun. Mass. Spectrom. 1999, 13, 1413-1422. 

Chamot-Rooke, J. van der Rest, G. Dalleu, A. Bay, S. Lemoine, J. The combination of electron capture dissociation and fixed charge derivatization increases sequence coverage for O-glycosylated and O-phosphorylated peptides. J. Am. Soc. Mass Spectrom. 2007,18,1405-1413. 

Marekov, L. N., Steinert, P. M. (2003) Charge derivatization by 4-sulfophenyl isothiocyanate enhances peptide sequencing by post-source decay matrix-assisted laser des-... 

Huang, Z. H., Wu, J., Roth, K. D., Yang, Y., Gage, D. A., Watson, J. T. (1997) A picomole-scale method for charge derivatization of peptides for sequence analysis by mass spectrometry. Anal Chem, 69,137-144. 

Strahler, j. R. Smelyanskiy, Y Lavine, G. Allison, J. Development of methods for the charge derivatization of peptides in polyacrylamide gels and membranes for their direct analysis using matrix-assisted laser desorption/ionization mass speetrometry. Int. J. Mass Spectrom. Ion Proa 1997,169/170, 111 126. 

CzBszAK, X. Morelle, W. Ricart, G. T taert, D. Lemoine, j. Localization of the O-glycosylated sites in peptides by hxed-charge derivatization with a phosphonium group. Anal. Chem. 2004, 76, 4320-4324. 

Electron donor molecules are oxidized in solution easily. Eor example, for TTE is 0.33V vs SCE in acetonitrile. Similarly, electron acceptors such as TCNQ are reduced easily. TCNQ exhibits a reduction wave at — 0.06V vs SCE in acetonitrile. The redox potentials can be adjusted by derivatizing the donor and acceptor molecules, and this tuning of HOMO and LUMO levels can be used to tailor charge-transfer and conductivity properties of the material. Knowledge of HOMO and LUMO levels can also be used to choose materials for efficient charge injection from metallic electrodes. 

Derivatized semiconductor photoelectrodes offer a way to design photosensitive interfaces for effecting virtually any redox process. Manipulation of interfacial charge transfer processes has been demonstrated using hydrolytically unstable redox... 

BSA possesses a total of 59 lysine e-amine groups (with only 30-35 of these typically available for derivatization), 1 free cysteine sulfhydryl (with an additional 17 disulfides buried within its three-dimensional structure), 19 tyrosine phenolate residues, and 17 histidine imidazole groups. The presence of numerous carboxylate groups gives BSA its net negative charge (pi 5.1). 

The correct ratio of lipid constituents is important to form stable liposomes. For instance, a reliable liposomal composition for encapsulating aqueous substances may contain molar ratios of lecithin cholesterol negatively charged phospholipid (e.g., phosphatidyl glycerol (PG)) of 0.9 1 0.1. A composition that is typical when an activated phosphatidylethanolamine (PE) derivative is included may contain molar ratios of phosphatidylcholine (PC) cholesterol PG derivatized PE of 8 10 1 1. Another typical composition using a maleimide derivative of PE without PG is PC male-imide-PE cholesterol of 85 15 50 (Friede et al., 1993). In general, to maintain membrane stability, the PE derivative should not exceed a concentration ratio of about l-10mol PE per lOOmol of total lipid. 

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