Group News

ASMS 2012

Murray Group at the poster session at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012
Venkatesulu Salla at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012
Machavaram Siva Pratap Reddy at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012
Chinthaka Seneviratne and Sung-Gun Park at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012
Yonathan Merid at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012
Murray Group at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012
Float Plane in Vancouver Harbor at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012
Float plane and boat at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012
Float planes at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012
Float plane taking off in Vancouver Harbor at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012
Two float planes in Vancouver Harbor at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012
Rainbow at the American Society for Mass Spectrometry meeting in Vancouver BC, 2012

Chapter 3 Links

Here are some examples of videos related to the content of Chapter 3 of Chemistry: the Central Science. You may find some of them a useful supplement to the assigned class material.

Stoichiometry

[youtube=http://www.youtube.com/watch?v=OjnuNRivedM]

Balancing Equations

[youtube=http://www.youtube.com/watch?v=YAutl-G7g4A] [youtube=http://www.youtube.com/watch?v=RnGu3xO2h74]

The Mole

[youtube=http://www.youtube.com/watch?v=tEn0N4R2dqA] [youtube=http://www.youtube.com/watch?v=BTRm8PwcZ3U] [youtube=http://www.youtube.com/watch?v=AsqEkF7hcII]

Mass Composition to Empirical Formula

[youtube=http://www.youtube.com/watch?v=xatVrAh2U0E] [youtube=http://www.youtube.com/watch?v=sXOIIEZh6qg]

Combustion Analysis

[youtube=http://www.youtube.com/watch?v=ebFP7onBbts] [youtube=http://www.youtube.com/watch?v=PCtR5hqBWjM] [youtube=http://www.youtube.com/watch?v=66ziUq6vRko]

Gram to Mole to Mole to Gram Problems

[youtube=http://www.youtube.com/watch?v=jFv6k2OV7IU] [youtube=http://www.youtube.com/watch?v=eQf_EAYGo-k]

Limiting Reactants

[youtube=http://www.youtube.com/watch?v=krioEzlRegc] [youtube=http://www.youtube.com/watch?v=VBuCEwTwV7Q] [youtube=http://www.youtube.com/watch?v=GY2Mav0_mGU] [youtube=http://www.youtube.com/watch?v=rESzyhPOJ7I] [youtube=http://www.youtube.com/watch?v=CMi9k8ts9r4] [youtube=http://www.youtube.com/watch?v=YNriRslOk9A]

Isolation and determination of the primary structure of a lectin protein from the serum of the american alligator (Alligator Mississippiensis)

doi:10.1016/j.cbpb.2011.11.001
Darville, Merchant, Maccha, Siddavarapu, Hasan, and Murray
Comp. Biochem Physiol. B

Alligator Lectin Protein Sequence (doi:10.1016/j.cbpb.2011.11.001)

Mass spectrometry in conjunction with de novo sequencing was used to determine the amino acid sequence of a 35 kDa lectin protein isolated from the serum of the American alligator that exhibits binding to mannose. The protein N-terminal sequence was determined using Edman degradation and enzymatic digestion with different proteases was used to generate peptide fragments for analysis by liquid chromatography tandem mass spectrometry (LC MS/MS). Separate analysis of the protein digests with multiple enzymes enhanced the protein sequence coverage. De novo sequencing was accomplished using MASCOT Distiller and PEAKS software and the sequences were searched against the NCBI database using MASCOT and BLAST to identify homologous peptides. MS analysis of the intact protein indicated that it is present primarily as monomer and dimer in vitro. The isolated 35 kDa protein was ~ 98% sequenced and found to have 313 amino acids and nine cysteine residues and was identified as an alligator lectin. The alligator lectin sequence was aligned with other lectin sequences using DIALIGN and ClustalW software and was found to exhibit 58% and 59% similarity to both human and mouse intelectin-1. The alligator lectin exhibited strong binding affinities toward mannan and mannose as compared to other tested carbohydrates.

Experimental Physical Chemistry Tenure Track Position at LSU

ASSISTANT/ASSOCIATE/FULL PROFESSOR

The Louisiana State University Department of Chemistry anticipates filling an Assistant/Associate/Full Professor (Experimental Physical Chemistry/Tenure-track) position with a starting date of August 13, 2012.

Required Qualifications: Ph.D. in chemistry or a related field; demonstrated excellence in teaching and research. Responsibilities: establish a strong, well-funded, widely recognized research program in experimental physical chemistry; teach at the undergraduate and graduate levels. An offer of employment is contingent on a satisfactory pre-employment background check.

Application deadline is November 28, 2011 or until a candidate is selected.

Applications at the Assistant Professor level should consist of a cover letter, curriculum vitae, summary of proposed research, and statement of teaching philosophy, preferably as a single PDF document; and three letters of recommendation.

Associate/Full Professor candidates should submit a letter of interest and curriculum vitae. Please submit materials electronically; see below. Arrange for letters of recommendation to be sent to Ms. Vickie Thornton (vthornton@lsu.edu), Experimental Physical Chemistry Search, Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803.

LSU IS AN EQUAL OPPORTUNITY/EQUAL ACCESS EMPLOYER

Apply online at https://lsusystemcareers.lsu.edu/applicants/Central?quickFind=53755

Particle Formation in Ambient MALDI Plumes

dx.doi.org/10.1021/ac201032g
Musapelo and Murray
Anal. Chem. 2011, 83, 6601–6608

The ablated particle count and size distribution of four solid matrix materials commonly used for matrix-assisted laser desorption ionization (MALDI) were measured with a scanning mobility particle sizer (SMPS) combined with a light scattering aerodynamic particle sizer (APS). The two particle sizing instruments allowed size measurements in the range from 10 nm to 20 μm. The four solid matrixes investigated were 2,5-dihydroxybenzoic acid (DHB), 4-nitroaniline (NA), α-cyano-4-hydroxycinnamic acid (CHCA), and sinapic acid (SA). A thin film of the matrix was deposited on a stainless steel target using the dried droplet method and was irradiated with a 337 nm nitrogen laser at atmospheric pressure. The target was rotated during the measurement. A large number of nanoparticles were produced, and average particle diameters ranged from 40 to 170 nm depending on the matrix and the laser fluence. These particles are attributed to agglomeration of smaller particles and clusters and/or hydrodynamic sputtering of melted matrix. A coarse particle component of the distribution was observed with diameters between 500 nm and 2 μm. The coarse particles were significantly lower in number but had a total mass that was comparable to that of the nanoparticles. The coarse particles are attributed to matrix melting and spallation. Two of the compounds, CHCA and SA, had a third particle size distribution component in the range of 10 to 30 nm, which is attributed to the direct ejection of clusters.

Infrared Laser Ablation Sample Transfer for MALDI and Electrospray

DOI: 10.1007/s13361-011-0163-3

Park and Murray
J. Am. Soc. Mass Spectrom. (2011)

We have used an infrared laser to ablate materials under ambient conditions that were captured in solvent droplets. The droplets were either deposited on a MALDI target for off-line analysis by MALDI time-of-flight mass spectrometry or flow-injected into a nanoelectrospray source of an ion trap mass spectrometer. An infrared optical parametric oscillator (OPO) laser system at 2.94 μm wavelength and approximately 1 mJ pulse energy was focused onto samples for ablation at atmospheric pressure. The ablated material was captured in a solvent droplet 1–2 mm in diameter that was suspended from a silica capillary a few millimeters above the sample target. Once the sample was transferred to the droplet by ablation, the droplet was deposited on a MALDI target. A saturated matrix solution was added to the deposited sample, or in some cases, the suspended capture droplet contained the matrix. Peptide and protein standards were used to assess the effects of the number of IR laser ablation shots, sample to droplet distance, capture droplet size, droplet solvent, and laser pulse energy. Droplet collected samples were also injected into a nanoelectrospray source of an ion trap mass spectrometer with a 500 nL injection loop. It is estimated that pmol quantities of material were transferred to the droplet with an efficiency of approximately 1%. The direct analysis of biological fluids for off-line MALDI and electrospray was demonstrated with blood, milk, and egg. The implications of this IR ablation sample transfer approach for ambient imaging are discussed.

A solid-phase bioreactor with continuous sample deposition for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

DOI: 10.1002/rcm.4921

Lee, Soper, and Murray
Rapid Commun. Mass Spectrom. 2011, 25, 693–699

We report the development of a solid-phase proteolytic digestion and continuous deposition microfluidic chip platform for low volume fraction collection and off-line matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Tryptic peptides were formed in an on-chip bioreactor and continuously deposited onto a MALDI target plate using a motor-driven xyz stage. The bioreactor consisted of a 4cmT200mmT50mm microfluidic channel with covalently immobilized trypsin on an array of 50mm diameter micropost structures with a 50 mm edge-to-edge inter-post spacing. A 50 mm i.d. capillary tube was directly attached to the end of the bioreactor for continuous sample deposition. The MALDI target plate was modified by spin-coating a nitrocellulose solution containing a MALDI matrix on the surface prior to effluent deposition. Protein molecular weight standards were used for evaluating the performance of the digestion and continuous deposition system. Serpentine sample traces 200 mm wide were obtained with a 30 fmol/mm quantity deposition rate and a 3.3 nL/mm volumetric deposition rate.