Alpha-cyano

The MALDI-TOF technique was first developed for the analysis of large biomolecules (Karas and others 1987). This technique presents some interesting characteristics. Of these, the high speed of analysis and the sensitivity of the technique have been pointed out as important advantages compared with other methods. In MALDI the samples are cocrystallized with a matrix that is usually composed of organic compounds, such as 3,5-dimethoxy-4-hydroxycinnamic acid (sinapic acid), 2, 4, 6 -trihydroxyacetophenone, a-cyano-4-hydroxycinnamic acid (alpha-cyano or alpha-matrix), and 2,5-dihydroxybenzoic acid (DHB). After the cocrystallization, the laser is fired and the matrix absorbs energy and allows a soft ionization of the samples. Afterward the ions are analyzed by a TOF mass spectrometer. 

Brooks, M.W. and J.M. Clark. 1987. Enhancement of norepinephrine release from rat brain synaptosomes by alpha cyano pyrethroids. Pestic. Biochem. Physiol. 28 127-139. 

Meacham CA, Brodfuehrer PD, Watkins JA, Shafer TJ (2008) Developmentally-regulated sodium channel subunits are differentially sensitive to alpha-cyano containing pyrethroids. Toxicol Appl Pharmacol 231 273-281... 

N1 - ERGOLINE-8-PROPIONAMIDE, 2-CHLORO-alpha-CYANO-6-METHYL-... 

ERSOLINE-8-alpha-PROPIONAHIDE. alpha-CYANO-4-HETHYl-... 

ERGOLINE-8-PROPIONAMIDE, 9, IO-OIOEHYORO-alpha-CYANO-4-HETHYL-... 

For non-quantitative LC-MALDI applications, derivatization chemistry is not restricted to compounds which allow a convenient incorporation of heavy isotopes. For example for improved MS/MS detection sensitivity, tryptic peptides were labeled with sulfonated coumarin-tags at the N-termini after guanidylation of lysines (Pashkova et al. 2005). Despite reduced MS sensitivity for arginine-terminated peptides (in alpha cyano-4-hydroxycinnamic acid matrix), formation of y-ions was enhanced in MS/MS by the second mobile proton provided from the sulfonic acid group. For a SCX fraction from a E.coli hydrolysate 50% more peptides and 30% more proteins could be identified by multiplexed LC-MALDI MS and MS/MS after derivatization. 

MALDI-TOF Mass Spectrometry. Peptide/detergent mixtures as well as purified peptides were analyzed using a Vestec LaserTec BenchTop II system (PerSeptive Biosystems). Peptides were mixed with alpha-cyano-4-hydroxycinnamic acid as previously described (4). 

Figure 3. MALDI-TOF mass spectrometry of peaks 1 (A-C) and 2 (D-F) purified after digestion of PVDF-bound transferrin using 1% RTX-100 (A, D), octylglucopyranoside (B, E), and decylglucopyranoside (C, F) as shown in Figure 2. Approximately 0.5% of the purified peptide (-150 fmole) was mixed with alpha-cyano-4-hydroxycinnamic acid and analyzed by MALDI-TOF mass spectrometry as described in Materials and Methods. Ninety percent of the peptide was amino terminally sequenced (Table II).

A novel class of N.N -diphenyl vinylogous urea herbicides was shown to have several strict structural requirements. All of the following are important for optimum herbicide activity an alpha-cyano... 

Table I. Ortho Substituted Alpha-Cyano Vinylogous Ureas C6H5N(CH3)CH=C(CN)CONH(ortho-X)Aryl...

Pyrethroids may conveniently be classified into two groups based on the chemical structure and toxic action (1 -Z8). Type I pyrethroids do not possess an alpha-cyano group and include many conventional ones such as allethrin, tetramethrin, phenothrin and permethrin. Type II pyrethroids possess a cyano group at the a position and include cyphenothrin, cypermethrin, deltamethrin and fenvalerate. 

The effect of single applications of esfenvalerate [S-alpha-cyano-3-phenoxybenzyl (S)-2-(4-chlorophenyl)-3-methylbutyrate] was examined (Lozano et al 1992) in a pond system containing plant and animal communities including the following macrophytes and phytoplankton, micro- and macroinvertebrates and fish (fathead minnows, bluegills, and northern redbelly dace (Phoxinus eos)) which were placed in enclosures. A range of toxicant exposure concentrations was employed, but at the lowest that were used, the concentrations of the toxicant were unmeasurable after 24 h. 

Matrix alpha-cyano-4-hydroxycinnamic acid (HCCA, 1 mg)... 

Gobom, J., Schuerenberg, M., Mueller, M., Theiss, D., Lehrach, H., and Nordhoff, E. (2001) Alpha-Cyano-4-HCCA affinity sample preparation. A protocol for MALDI-MS peptide analysis in proteomics. Anal. Chem. 73, 434 38. 

The selection of the matrix is of major importance in MALDI because the amount of energy transferred to the analyte is matrix-specific. Examples of matrices include dihydroxybenzoic acid, alpha-cyano-4-hydroxy-cinnamic acid, and sinapinic acid (also called sinapic acid). Alpha-cyano is the choice for peptides up to 5 kDa, while sinapinic acid is used for larger peptides and proteins. The reason for the changeover from one matrix to the other is that alpha-cyano transfers larger amounts of energy to analytes than does sinapinic acid, resulting in the destruction of larger peptides and proteins. Samples and matrices are preferably prepared in the same solvents, e.g., an acetonitrileiwater (1 1 v/v) mixture that may contain 0.1-1% trifluoroacetic acid. The concentration of the matrix is 10 mg/ml. The simplest approach with alpha-cyano and sinapinic acid, and an acetonitrile water solvent mixture, is to prepare saturated... 

Martin, S.A., and Pappin, D.J. (2004) Suppression of alpha-cyano-4-hydroxydnnamic add matrix dusters and reduction of chemical noise in MALDI-TOF mass spectrometry. Anal. 

Fourier transform ion cyclotron resonance Full-width at half-maximum, the standard way of deter- mining peak width. It is used to calculate resolving power (see below). alpha-Cyano-4-hydroxycinnamic acid Ion cyclotron resonance Infrared... 

For the MALDI-MS analysis of intact proteins, FI CCA (alpha-cyano-4-hydroxycinnamic acid), SA (sinapinic acid) or DHB (2,5-dihydroxybenzoic acid) matrices and the dried-droplet deposition method for sample preparation are typically used [13, 14] (Table 3.1). Depending on the properties of the protein, it is often necessary to test a series of solvents and matrices to optimize the outcome of the MALDI-MS experiment. Peptides and small proteins below molecular weight 20000 Da are often amenable to analysis using HCCA matrix and reflector TOF-MS mode, whereas larger proteins may produce better results with SA or DHB matrix in the linear TOF-MS mode. Hydrophobic proteins can be analyzed using the HCCA matrix dissolved in high concentrations of formic acid (up to 30%) [15]. When using cirmamic acid matrices, SA and HCCA, and the... 

ACN acetonitrile DHAP 2,6-dihydroxyacetophenone DHB 2,5-dihydroxybenzoic add HCCA alpha-cyano-4-hydroxydnnamic add SA sinapinic add THAP 2,4,6-trihydroxyacetophenone. 

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