The Emergence of Mass Spectrometry in Biochemical Research Discussion

Anonymous
timer Asked: Apr 10th, 2019
account_balance_wallet $20

Question Description

read the paper then please answer the following questions each one in separate answer


What is the primary difference between MALDI and ESI with respect to charge state generation?

What is the role of H/D exchange in biological mass spectrometry (i.e. what does it tell you)?

What two classes of biopolymers can be sequenced using MALDI and ESI combined with tandem MS?

Attachment preview

Article: The emergence of mass spectrometry in biochemical research 

Unformatted Attachment Preview

Proc. Nati. Acad. Sci. USA Vol. 91, pp. 11290-11297, November 1994 Review The emergence of mass spectrometry in biochemical research Gary Siuzdak The Scripps Research Insthtte, Departent of Chemistry, 10666 North Torrey Pines Road, La Jolla, CA 92037 The initial steps toward ABSTRACT routinely applying mass spectrometry in the biochemical laboratory have been achieved. In the past, maw spectrometry was confined to the realm of small, relatively stable molecules; large or thermally labile molecules did not survive the desorpdion and ionization processes intact. Electrospray ionization (ESI) and matrixassisted laser desorption/ionization (MALDI) mass spe met allow for the analysis of both small and large biomolecules through "mild" desorption and ionization methods. The use of ESI and MALDI mass spectrometry extends beyond simple characterization. Noncovalent interactions, protein and peptide sequencing, DNA sequencing, protein fdding, in vitro drug analysis, and drug discovery are among the areas to which ESI and MALDI mass spectrometry have been applied. This review summarizes recent developments and major contributions in mas spectrometry, focusing on the applications of MALDI and ESI mass spectrometry. Advances in chemical technology have been the engine powering the biotechnology industry. Analytical chemists have added fresh impetus to bioresearch with two new mass spectrometry ionization tools: electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). Commercial availability of these instruments has made routine the analysis of compounds including proteins, peptides, carbohydrates, oligonucleotides, natural products, and drug metabolites. ESI and MALDI mass spectrometry offer picomole-to-femtomole sensitivity, enabling the direct analysis of biological fluids with a minimum amount of sample preparation. These techniques can be used to measure the mass of biomolecules >200,000 Da, to provide structural information, and to detect noncovalent complexes with molecular weight ac- curacy on the order of ±0.01%. They signify another dimension in molecular characterization through a new level of sensitivity, accuracy, and mass range. Mass spectrometry is based on producing, differentiating, and detecting ions in the gas phase. The transfer of small molecules into the gas phase has traditionally been accomplished by thermal vaporization; however, thermal vaporization for biopolymers and other nonvolatile or dry gas and/or A. heat and/or dry gas vacuum pumps FIG. 1. ESI source. thermally unstable molecules has little use. In fact, the search for ionization sources that would transfer large, thermally labile molecules into the gas phase without degradation has occupied mass spectrometrists for many years. It has largely been the development of ESI and MALDI that have made routine what was, until recently, impossible. The trick has been forming ions in the gas phase; once formed, the ions can be directed electrostatically into a mass analyzer that differentiates the ions according to their mass-to-charge ratio (m/z). Although the analyzers have not changed significantly in the past two decades, the changes that have been made have been largely stimulated by the development of the ESI and MALDI ionization sources. Both ESI and MALDI-MS support biochemical research, each having unique capabilities, as well as some fundamental similarities. Although there are many exciting examples of how they are being used as bioanalytical tools, their basic utility in molecular characterization should not be underestimated. ESI and MALDI-MS offer a rapid, simple, and accurate means of obtaining molecular weight information on a wide range of compounds. Their utility for mass measurement meets the needs of chemists and biologists alike, facilitating routine characterization in small molecule synthesis, protein synthesis, and compounds obtained directly from biological matrices. ESI The utility of ESI (1-9) lies in its ability to produce singly or multiply charged gaseous ions directly from an aqueous or aqueous/organic solvent system by cre11290 ating a fine spray of highly charged droplets in the presence of a strong electric field (Fig. 1) (8). The sample solution is typically sprayed from the tip of a metal syringe maintained at -4000 V. Dry gas, heat, or both are applied to the highly charged droplets, causing the solvent to evaporate. Evaporation causes the droplet size to decrease, while surface charge density increases. Ions are transferred to the gas phase as a result oftheir expulsion from the droplet and then directed into a mass analyzer through a series of lenses. Typically, ESI is interfaced with quadrupole mass analyzers because quadrupoles tolerate high pressures (10-5 torr; 1 torr = 133.3 Pa) and have good resolving power (=2000). An intrinsic property of all mass analyzers (including quadrupole mass analyzers) is that they separate ions according to their mass-to-charge ratio (m/z), not the mass. This is often a point of confusion, especially with the ESI techniques, which typically generate multiply charged ions (Fig. 2). An advantage of multiple charging is that a mass analyzer with a relatively small m/z range (quadrupole instruments) can be used to observe very large molecules. The data generated via multiple charging can then be used to determine molecular weight. Another advantage of multiple charging is that more accurate molecular weight can be obtained from the distribution of multiply charged peaks. The mass spectrum of egg white lysozyme (in Fig. 2) illustrates the ability of the ESI technique to generate multiply charged ions. It is especially inAbbreviations: ESI, electrospray ionization; MALDI, matrix-assisted laser desorption/ ionization; FTMS, Fourier-transform ion cyclotron resonance mass spectrometry. Proc. Nadl. Acad. Sci. USA 91 (1994) Rmeview: Siuzdak HPLC Chromatogram 0.25. 10+ 1432 100' egg white tysozyme 11291 C A B 75, 50 25 11+ 9+ 1302 1592 S 8+ 12+ 1194 1250 A..~~19 1750 1500 time (minutes) m/z HPLC-MS FIG. 2. ESI mass spectrum of egg white lysozyme. The molecular weight can be calculated from the equation: Mr = (mass-tocharge ratio x total charge) - total mass of charging species or Mr = (m/z x z) - z (if charging species are protons). Sample calculations for egg white lysozyme are as follows: m/z= 1302.5, z = 11 (+), Mr = (1302.5 x 11) - 11 = 14,317; m/z = 1432.4, z = 10 (+), Mr = (1432.4 x 10) - 10 = 14,317; m/z = 1591.7, z = 9 (+), Mr = (1591.7 x 9) -9 = 14,317. teresting to note that an instrument with a mass range of Purchase answer to see full attachment

Tutor Answer

Knutsen
School: UCLA

Hello there, have a look at the complete paper. In case of any concern, feel free to alert me.Regards

Running head: MALDI AND ESI

1

MALDI and ESI

Student’s Name
Institutional Affiliation

MALDI AND ESI

2

What is the primary difference between MALDI and ESI concerning charge state
generation?
In normal environments, MALDI causes the +1 ions of the charges to proteins. The
proteins imparted usually possess occasional charges of +2 and +3 ions. The charge in MALD...

flag Report DMCA
Review

Anonymous
Good stuff. Would use again.

Brown University





1271 Tutors

California Institute of Technology




2131 Tutors

Carnegie Mellon University




982 Tutors

Columbia University





1256 Tutors

Dartmouth University





2113 Tutors

Emory University





2279 Tutors

Harvard University





599 Tutors

Massachusetts Institute of Technology



2319 Tutors

New York University





1645 Tutors

Notre Dam University





1911 Tutors

Oklahoma University





2122 Tutors

Pennsylvania State University





932 Tutors

Princeton University





1211 Tutors

Stanford University





983 Tutors

University of California





1282 Tutors

Oxford University





123 Tutors

Yale University





2325 Tutors