Synthesis of Uniform Peptide Libraries and Methods for Physico-Chemical Analysis

The “One-Bead-One-Compound” Combinatorial Library Method

“…In this case the synthesis of a library containing 20 amino acids in the fixed position and 20 amino acids in positions requiring equimolar incorporation of amino acids would require the use of 400 reaction vessels. Alternatively one can use a mixture of amino acids in which the ratio is adjusted according to the reactivity of the particular protected building block, ,− or double or triple coupling of subequimolar (0.8 molar) amounts of equimolar mixtures of amino acids. − Equimolarity of incorporation is not an issue in real one-bead-one-compound libraries, where equimolarity is a priori achieved by the synthesis of only one compound on each bead; however, it becomes important in techniques synthesizing multiplicity of peptides (motifs) on each particular bead (see below).…”

“…Computer-generated distribution profiles (see e.g. ref ) can be compared with the actual profile obtained from the library sample. , Depending on the ionization technique, the theoretical profile may need to be modified with a correction factor. For example peptide libraries evaluated by FAB mass spectrometry should take into consideration high proton affinity of arginine after multiplication of abundances of arginine-containing peptides by the factor of 10 the correspondence of theoretical and experimental spectrum can be achieved .…”

Evaluation of high performance liquid chromatography/electrospray mass spectrometry with selected ion monitoring for the analysis of large synthetic combinatorial peptide libraries

“…Most of the differences in the relative intensities of ions, as a function of molecular mass, can be explained by ESI discrimination effects, mainly by the large variation in the fraction of peptides in a molecular mass interval which contain Arg, 14 for which a better ionization efficiency is expected. However, the shape of the '14 Da modulation', 22,26 caused by the 14 Da spacing between some residue masses, can be considered a better analytical criterion because it is a direct representation of the molecular diversity of the library.…”

“…14 Analysis of a complex library can be simply done by comparing the low resolution mass spectrum with the theoretical spectrum, as has been done in several instances 14,16,[22][23][24][25] and for which the theoretical assessment was discussed in detail. 26 The validity of such a comparison is based on the assumption that every compound gives a single and predictable ion with a constant yield.…”

Teaching Editorial - Bioanalytical Mass Spectrometry: Many Flavors to Choose

“…The analytical characterization of these complex mixtures is a challenging task. Electrospray ionization MS is a useful method to identify potential problems in the synthesis of peptide libraries (205) and, in combination MS/MS, provides a rapid and reliable method to determine the composition (206). However, identification of the active compounds from these complex mixtures is a difficult task.…”