The rapid and enormous expansion in the biotechnology revolution has caused increased interest in determining exact molecular weights of biological systems. Mass spectrometry offers a quick and convenient method for determining accurate molecular weights of biological samples including peptides, proteins, oligonucleotide and oligosaccharides. Matrix-Assisted Laser Desorption Ionization and Electrospray Ionization are the two predominant mass spectrometry techniques used for the development of biological assays.

During the MALDI process singly-charged analyte ions are produced after desorption/ionization from a matrix using a nitrogen laser. For example, in our laboratory we utilize MALDI to detect amiodarone, an anti-arrhtymic drug, in biopsies of explanted human hearts from cardiac transplant recipients. In another study MALDI is used to track the decomposition of PCR primers over various periods of time ranging from 1 day to 10 years.

In contrast to MALDI, the ESI method ionizes an analyte to form charged species through desolvation of microscopic droplets. A resultant ESI spectrum contains a multiply protonated envelope of various mass-to-charge ratios. ESI can be used to track the activity of protein kinases as well as the modulation of the kinase activity. To demonstrate the effectiveness of using ESI-MS as a kinase assay, one of the best-characterized kinases, cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) is studied. ESI can also be utilized to study the conformational changes of protein structures as they undergo desolvation. It is also possible to analyze the denaturing of oligonucleotide strands as the sample enters the gaseous phase.

‡ Undergraduate Student
* Graduate Student

Xinhua Guo*, Zhiqiang Liu, Shuying Liu, Catherine M. Bentzley, Michael F. Bruist, "Structural Features of the L-Argininamide-Binding DNA Aptamer Studied with ESI- FTMS", Analytical Chemistry 78(20), 7259-7266 (2006).

Jingjun Huang; Rodney J. Wigent; Catherine M. Bentzley; Joseph B. Schwartz, "Nifedipine Solid Dispersion in Microparticles of Ammonio Methacrylate Copolymer and Methylcellulose Binary Blend for Controlled Drug Delivery Effect of Drug Loading on Release Kinetics", International Journal of Pharm. 319, 44-54 (2006).

Jingjun Huang, Rodney Wigent, Catherine Bentzley and Joseph Schwartz, "Nifedipine Molecular Dispersion in Microparticles of Ammonia Methacrylate Copolymer and Ethylcellulose Binary Blend for Drug Controlled Delivery: Effect of Drug Loading on Release Kinetics”, Drug Development and Industrial Pharm. 32(10), 1185-1197 (2006).

Ying Li, Catherine Bentzley and Joan B. Tarloff, "Comparison of Para-Aminophenol Cytotoxicity in Rat Renal Epithelial Cells & Hepatocytes", Toxicology January (2005).

Xinhua Guo*, Michael F. Bruist, Darryl L. Davis, Catherine M. Bentzley, "Secondary Structural Characterization of Oligonucleotide Strands Using Electrospray Ionization Mass Spectrometry", Nucleic Acid Research, June 28, (2005).

X. Guo*; D. L. Davis; M. F. Bruist; C.M Bentzley, 2004, "Structural Characterization of Oligonucleotides by Energetic Collision within the Orifice-Skimmer Region of Electrospray Ionization Mass Spectrometry", Journal of the American Society for Mass Spectrometry (in press).

J. Dally*; J. Gorniak; R. Bowie; C. Bentzley, "Quantitation of Underivatized Free Amino Acids in Mammalian Cell Culture Media Using Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry", Analytical Chemistry 75, 5046 - 5053 (2003).

Darryl L. Davis*, Edward O'Brien‡ and Catherine Bentzley, "Analysis of the Degradation of Oligonucleotide Strands During the Freezing/Thawing Processes Using MALDI-MS", Analytical Chemistry 20, 5092-5096 (2000).

W. Bartolini, C.M. Bentzley, M.V. Johnston, B.S. Larsen, "Identification of Overhangs in Double Stranded DNA by Enzymatic Digestion with MALDI Analysis", J. Am. Soc. Mass Spectrometry 10, 521-528 (1999).

C. Bentzley, M. Johnston, B. Larsen, "Base Specificity of Oligonucleotide Digestion by Calf Spleen Phosphodiesterase with Matrix-Assisted Laser Desorption Ionization Analysis", Analytical Biochemistry 258, 31-37 (1998).

C. Bentzley, M. Johnston, B. Larsen, S. Gutteridge, "Oligonucleotide Sequence and Composition Determined by Matrix-Assisted Laser Desorption/Ionization", Analytical Chemistry 13, 2141-46 (1996).