Hydrophobic matching, definition

In general, MALDI and ESI are of comparable sensitivity (femtomolar to low picomolar levels of peptides/ proteins) however, it is impossible to make definitive comparisons for two reasons. First, there have been, and continue to be, technological advances improving the sensitivity of both techniques whereby, for example, the use of special hydrophobic surfaces on MALDI targets has been matched by the development of nano-ESI. Second, it has been observed that in complex proteomic analyses, perhaps only 30-50% of all proteins are adequately ionized by both ESI and MALDI, with the remainder being best ionized by either ESI or MALDI alone. Thus there is a good case to be made for the use of both techniques in a comprehensive proteomic analysis (Table 5). 

The appearance of CMC s for polysoaps bearing particularly short hydro-phobic tails [193] is rather a semantic problem as these examples do not match the original definition of polysoaps anymore. If the hydrophobe tails are too short, no intramolecular aggregation can take place as evident from viscosity measurements [24, 133, 193], and intermolecular aggregation is needed to reduce hydrophobic interactions. 

Enzymes are comprised of proteins which have definitive primary structures that can organize into secondary, tertiary and even quaternary structures. The enzyme consists of a peptide framework that contains cavities in which the catalytically reactive centers are incorporated. The enzyme protein is typically about 20-40 nm in size. The catalytically reactive centers can be part of the peptide that builds the enzyme framework such as carboxylic acid groups, or consist of cationic centers such as the porphyrins or nonreducible cations as Zn " " or Mg " " directly attached to the protein cavity. As mentioned earlier, the external part of the enzyme is hydrophilic and the internal microcavity is hydrophobic, with the possible exception of the often polar reaction center. In enzymatic reactions, the match between shape and size of reactant or product and catalytic center cavity is important. 

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