Acylhydrazide and Isatin Schiff Bases as Alternate UV-Laser Desorption Ionization (LDI) Matrices for Low Molecular Weight (LMW) Peptides Analysis

Syed Ghulam Musharraf, Aisha Bibi, Najia Shahid, Muhammad Najam-ul-Haq, Momin Khan, Muhammad Taha, Uzma Rasool Mughal, Khalid Mohammed Khan

Department of Chemistry, Bahauddin Zakariya University, Multan, Pakistan.
Hussain Ebrahim Jamal Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan.
Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan.

DOI: 10.4236/ajac.2012.312104                

Abstract

Matrix-assisted laser desorption/ionization (MALDI) is a preferred and widely used mass spectrometric technique for the analysis of macromolecules. Limited UV-LDI matrices are available for the analysis of biomolecules due to the restricted structural features to serve in the laser desorption/ionization mechanism with a problem of background signals appearing in the low mass region. This paper describes the application of Schiff base derivatives of acylhydrazide and isatin as alternate UV-LDI matrices for the analysis of peptides with significantly low background signals. Thirty one compounds have been successfully employed as matrices for the analysis of low molecular weight (LMW) peptides (<2000 Da) including bradykinin and renin substrate tetra-decapeptide. Bovine serum albumin (BSA)-digest was also analyzed and identified through database search against Swiss-Prot by using MASCOT. The MS measurements were recorded by using dried droplet sample preparation procedures by mixing the matrix solution with analyte at a volume ratio of 1:2. Finally, LMW organic compounds (<500 Da) were also analyzed by the synthesized matrix materials which showed better S/N ratios and minimal background signals for low mass range in comparison to the comparable results with α-Cyano-4-hydroxycinnamic acid (HCCA), a preferred choice for peptide analysis.

Keywords

MALDI-MS; LDI Matrix; Acylhydrazide Schiff Bases; Bis-Schiff Bases of Isatin; Schiff Bases of Isatin; Peptides

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	J. Gross and K. Strupat, “Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Applied to Biological Macromolecules,” Trends in Analytical Chemistry, Vol. 17, No. 8-9, 1998, pp. 470-484. doi:10.1016/S0165-9936(98)00060-0
[2]	D. J. Rousell, S. M. Dutta, M. W. Little and K. K. Murray, “Matrix-Free Infrared Soft Laser Desorption/Ionization,” Journal of Mass Spectrometry, Vol. 39, No. 10, 2004, pp. 1182-1189. doi:10.1002/jms.706
[3]	A. Holle, A. Haase, M. Kayser and J. Hohndorf, “Optimizing UV Laser Focus Profiles for Improved MALDI Performance,” Journal of Mass Spectrometry, Vol. 41, No. 6, 2006, pp. 705-716.
[4]	J. Krause, M. Stoeckli and U. P. Schlunegger, “Studies on the Selection of New Matrices for Ultraviolet Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry,” Rapid Communication in Mass Spectrometry, Vol. 10, No. 15, 1996, pp. 1927-1933. doi:10.1002/(SICI)1097-0231(199612)10:15<1927::AID-RCM709>3.0.CO;2-V
[5]	P. Juhasz, P. Costello and K. Biemann, “Matrix-Assisted Laser Desorption Ionization Mass Spectrometry with 2- (4-Hydroxyphenylazo) Benzoic Acid Matrix,” Journal of the American Society for Mass Spectrometry, Vol. 4, No. 5, 1993, pp. 399-409. doi:10.1016/1044-0305(93)85005-I
[6]	K. J. Wu, A. Steding and C. H. Becker, “Matrix-Assisted Laser Desorption Time-of-Flight Mass Spectrometry of Oligonucleotides Using 3-Hydroxypicolinic Acid as an Ultraviolet-Sensitive Matrix,” Rapid Communication in Mass Spectrometry, Vol. 7, No. 2, 1993, pp. 142-146. doi:10.1002/rcm.1290070206
[7]	J. O. Metzger, R. Woisch, W. Tuszynski and R. Angermann, “New Type of Matrix for Matrix-Assisted Laser Desorption Mass Spectrometry of Polysaccharides and Proteins,” Fresenius Journal of Analytical Chemistry, Vol. 349, No. 6, 1994, pp. 473-474. doi:10.1007/BF00322937
[8]	U. Pieles, W Zürcher, M Sch?r and H. Moser, “Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry: A Powerful Tool for the Mass and Sequence Analysis of Natural and Modified Oligonucleotides,” Nucleic Acids Research, Vol. 21, No. 14, pp. 3191-3196.
[9]	Y. Dai, R. M. Whittal, C. A. Bridges, Y. Isogai, O. Hindsgaul and L. Li, “Matrix-Assisted Laser Desorption Ionization Mass Spectrometry for the Analysis of Monosulfated Oligosaccharides,” Carbohydrate Research, Vol. 304, No. 1, 1997, pp. 1-9. doi:10.1016/S0008-6215(97)00195-X
[10]	M. C. Fitzgerald, G. R. Parr and L. M. Smith, “Basic Matrices for the Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry of Proteins and Oligonucleotides,” Analytical Chemistry, Vol. 65, No. 22, 1993, pp. 3204-3211. doi:10.1021/ac00070a007
[11]	Y. Fukuyama, R. Tanimura, K. Maeda, M. Watanabe, S. Kawabata, S. Iwamoto, S. Izumi and K. Tanaka, “Alkylated Dihydroxybenzoic Acid as a MALDI Matrix Additive for Hydrophobic Peptide Analysis,” Analytical Chemistry, Vol. 84, No. 9, 2012, pp. 4237-4243. doi:10.1021/ac300540r
[12]	S. Martic, J. D. Brennan, M. A. Brook, S. Ackloo and N. Nagy, “Towards the Development of a Covalently Tethered MALDI System—A Study of Allyl-Modified MALDI Matrixes,” Canadian Journal of Chemistry, Vol. 85, No. 1, 2007, pp. 66-76. doi:10.1139/v06-185
[13]	Z. Guo, Q. Zhang , H. Zou, B. Guo and J. Ni, “A Method for the Analysis of Low-Mass Molecules by MALDITOF Mass Spectrometry,” Analytical Chemistry, Vol. 74, No. 7, 2002, pp. 1637-1641. doi:10.1021/ac010979m
[14]	G. McCombie and R. Knochenmuss, “Small-Molecule MALDI using the Matrix Suppression Effect to Reduce or Eliminate Matrix Background Interferences,” Analytical Chemistry, Vol. 76, No. 17, 2004, pp. 4990-4997. doi:10.1021/ac049581r
[15]	F. O. Ayorinde, P. Hambright, T. N. Porter and Q. L. Keith, “Use of Meso-Tetrakis (Pentafluorophenyl) Porphyrin as a Matrix for Low Molecular Weight Alkyl Phenol Ethoxylates in Laser Desorption/Ionization Time-of-Flight Mass Spectrometry,” Rapid Communication in Mass Spectrometry, Vol. 13, No. 24, 1999, pp. 2474-2479. doi:10.1002/(SICI)1097-0231(19991230)13:24<2474::AID-RCM814>3.0.CO;2-0
[16]	A. Tholey and E. Heinzle, “Ionic (Liquid) Matrices for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry—Applications and Perspectives,” Analytical and Bioanalytical Chemistry, Vol. 386, No. 1, 2006, pp. 24-37. doi:10.1007/s00216-006-0600-5
[17]	D. W. Armstrong, L. Zhang, L. He and M. L. Gross, “Ionic Liquids as Matrixes for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry,” Analytical Chemistry, Vol. 73, No. 15, 2001, pp. 3679-3686. doi:10.1021/ac010259f
[18]	M. Najam-ul-Haq, M. Rainer, C. W. Huck, P. Hausberger, H. Kraushaar and G. K. Bonn, “Nanostructured Diamond-Like Carbon on Digital Versatile Disc as a Matrix-Free Target for Laser Desorption/Ionization Mass Spectrometry,” Analytical Chemistry, Vol. 80, No. 19, 2008, pp. 7467-7472.
[19]	J. Wei, J. M. Buriak and G. Siuzdak, “Desorption-Ionizationmass Spectrometry on Porous Silicon,” Letters to Nature, Vol. 399, No. 77, 1999, pp. 243-246. doi:10.1038/20400
[20]	S. Zhang, Y. Chen, J. A. Liu, S. X. Xiong, G. H. Wang, J. Chen and G. Q. Yang, “New Matrix of MALDI-TOF MS for Analysis of Small Molecules,” Chinese Chemical Letters, Vol. 20, No. 12, 2009, pp. 1495-1497. doi:10.1016/j.cclet.2009.06.031
[21]	T. Kinumi, T. Saisu, M. Takayama and H. Niwa, “Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Using an Inorganic Particle Matrix for Small Molecule Analysis,” Journal of Mass Spectrometry, Vol. 35, No. 3, 2000, pp. 417-422. doi:10.1002/(SICI)1096-9888(200003)35:3<417::AID-JMS952>3.0.CO;2-#
[22]	S. Ren, L. Zhang, Z. Cheng and Y. Guo, “Immobilized Carbon Nanotubes as Matrix for MALDI-TOF-MS Analysis: Applications to Neutral Small Carbohydrates,” Journal of the American Society for Mass Spectrometry, Vol. 16, No. 3, 2005, pp. 333-339. doi:10.1016/j.jasms.2004.11.017
[23]	X. Dong, J. Cheng, J. Li and Y. Wang, “Graphene as a Novel Matrix for the Analysis of Small Molecules by MALDI-TOF MS,” Analytical Chemistry, Vol. 82, No. 14, 2010, pp. 6208-6214. doi:10.1021/ac101022m
[24]	H. Kim, J. Lee, S. Park, H. W. Ro, D. Y. Yoo and D. Y. Yoon, “Observation of Low Molecular Weight Poly (Methylsilsesquioxane)s by Graphite Plate Laser Desorption/ Ionization Time-of-Flight Mass Spectrometry,” Analytical Chemistry, Vol. 72, No. 22, 2000, pp. 5673-5678. doi:10.1021/ac0003899
[25]	M. J. Dale, R. Knochenmuss and R. Zenobi, “Graphite/ Liquid Mixed Matrices for Laser Desorption/Ionization Mass Spectrometry,” Analytical Chemistry, Vol. 68, No. 19, 1996, pp. 3321-3329. doi:10.1021/ac960558i
[26]	C. Black, C. Poile, J. Langley and J. Herniman , “The Use of Pencil Lead as a Matrix and Calibrant for Matrix-Assisted Laser Desorption/Ionization,” Rapid Communication in Mass Spectrometry, Vol. 20, No. 7, 2006, pp. 1053-1060. doi:10.1002/rcm.2408
[27]	G. J. Langley, J. M. Herniman and M. S. Townell, “2B Or Not 2B, That is the Question: Further Investigations into the Use of Pencil as a Matrix for Matrix-Assisted Laser Desorption/Ionization,” Rapid Communication in Mass Spectrometry, Vol. 21, No. 2, 2007, pp. 180-190. doi:10.1002/rcm.2827
[28]	K. M. Khan, M. Khan, M. Ali, M. Taha, S. Rasheed, S. Perveen and M. I. Choudhary, “Synthesis of Bis-Schiff Bases of Isatins and their Antiglycation Activity,” Bioorganic & Medicinal Chemistry, Vol. 7, No. 22, 2009, pp. 7795-7801. doi:10.1016/j.bmc.2009.09.028
[29]	K. M. Khan, U. R. Mughal, Samreen, S. Perveen and M. I. Choudhary, “Schiff Bases of Isatin: Potential Anti-Leishmanial Agents,” Letters in Drug Design & Discovery, Vol. 5, No. 4, 2008, pp. 243-249. doi:10.2174/157018008784619915
[30]	M. W. F. Neilen, “MALDI Time-of-Flight Mass Spectrometry of Synthetic Polymers.” Mass Spectrometry Reviews, Vol. 18, No. 5, 1999, pp. 309-344. doi:10.1002/(SICI)1098-2787(1999)18:5<309::AID-MAS2>3.0.CO;2-L
[31]	S. F. Macha, P. A. Limbach and P. J. Savickas, “Application of Nonpolar Matrices for the Analysis of Low Molecular Weight Nonpolar Synthetic Polymers by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry,” Journal of the American Society for Mass Spectrometry, Vol. 11, No. 8, 2000, pp. 731-773. doi:10.1016/S1044-0305(00)00137-9