4-HCCA

Note It is commonplace to use acronyms rather than compound names for matrices. However, these are not always consistently used, e.g., a-CHC, 4-HCCA, CHCA, and CCA all refer to a-cyano-4-hydroxycinnamic acid. Others may be easily confused, e.g., nicotinic acid (NA) and 9-nitroanthracene (9-NA). 

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. 

Unlike the simulations which only consider particle-cluster interactions discussed earlier, hierarchical cluster-cluster aggregation (HCCA) allows for the formation of clusters from two clusters of the same size. Clusters formed by this method are not as dense as clusters formed by particle-cluster simulations, because a cluster cannot penetrate into another cluster as far as a single particle can (Fig. 37). The fractal dimension of HCCA clusters varies from 2.0 to 2.3 depending on the model used to generate the structure DLA, RLA, or LTA. For additional details, the reader may consult Meakin (1988). 

Fig. 37. Typical clusters obtained by diffusion-limited aggregation (DLA). Top Two-dimensional diffusion-limited aggregation. Bottom Reaction-limited hierarchical cluster-cluster aggregation (HCCA) (Meakin, 1988 with permission, from the Annual Review of Physical Chemistry, Vol. 39. by Annual Reviews www.Annual/Reviews.org).

Trihydroxyacetophenone (THAP) THAP can be used for the analysis of oligosaccharides and can offer improved sensitivity for detection of acidic glycopeptides over HCCA.37 Ionization with THAP can be improved with the addition of di-ammonium hydrogencitrate to limit cation adduction... 

Fig. 16.19. Mass spectrometry of WIN antiviral drug, (a) DIOS-MS spectrum ofWIN deposited upon porous silicon. Inset DIOS-PSD-MS spectrum of WIN. (b) MALDI-MS spectrum of WIN dispersed in a-cyano-4-hydroxycinnamic acid (HCCA). (c) Attempted...

Figure 4a MALDI-TOF mass spectral analysis of H-Thr-Arg-Asn-Leu-Ala-Asp-Gln-Glu-Asp-NH2. The spectrum was acquired on a TofSpec SE (Micromass) mass spectrometer equipped with a nitrogen laser and a reflectron, using a peptide solution of approximately 10 pmol//u,L and HCCA (Hewlett-Packard) as the matrix.

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

HCCA (0.67 mg/mL in ethanol acetone, 2 1). Dissolve approximately 1 mg HCCA in 500 pL acetone to make a 2-mg/mL stock solution. The matrix usually takes 5-10 min to completely dissolve at room temperature. We usually start the magnetic beads fractionation while waiting for the matrix to dissolve. Then add one part of above stock solution to two parts ethanol (e.g. 100 pL stock solution to 200 pL ethanol). Prepare the matrix solution daily. 

MCDO or HCCA H AVd1Ci4 diKrvlJ-t-r di H (coki(cn2> q[Pg.484]

Mixtures of several different matrices have been reported for an improved performance, for example, 1 1 (w/w) mixtures between HCCA and DHB resulted in a lowered chemical noise and slightly improved sequence coverages [148]. However, so far only DHBs (a mixture of 90-95% 2,5-DHB and 5-10% 2-hydroxy-5-methoxybenzoic acid) has found relatively widespread appHcation for proteins [149]. The additive soflens the desorption and Hmits the small neutral loss, thereby improving mass resolution. A mixture of different trihy-droxyacetophenones is sometimes used for the analysis of nucleic acids [150]. 

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