Heuristic pattern recognition analysis of carbon-13 nuclear magnetic resonance spectra

Abstract

dimerization reaction (eq 6) is uncertain, but bridged structures containing one OHbridge and another containing one OHand one deprotonated amide nitrogen bridge have been proposed1 23456 for the analogous glycylglycine complex, Cu2(H-iGlygly)2(OH)-. Since KO for the formation of these dimers is the same (Table I) for all isomers of Leu-Leu, it appears that there is relatively little peptide rearrangement during dimer formation and also there is probably little contact between the two peptide ligands in the dimer. Thus the structure with one OHgroup bridging the two Cu(H-íL) residues via the Cu(II) atoms appears to be the most probable.

Classification of binary carbon-13 nuclear magnetic resonance spectra

“…In previous papers, investigations of a number of heuristic pattern recognition strategies for the computer-assisted interpretation of nuclear magnetic resonance spectra were reported (1)(2)(3)(4)(5). The impetus for this work was our belief that the sensitivity of I3C chemical shifts to structure variation and the widespread availability of instrumentation for routine natural abundance 13C spectral measurements made this structure elucidation technique an imperative target of pattern recognition research.…”

“…49, NO. 14, DECEMBER 1977 Earlier work had relied, for training of categorizers, exclusively on a set of 500 spectra drawn from the Johnson and Jankowski collection (6) and was primarily devoted to studies of the merits of various data preprocessing techniques (1)(2)(3). In this paper, results made possible by the use of a new and larger carbon-13 NMR data base containing close to four thousand "C NMR spectra are reported.…”

“…Computation Methods. Pattern classification using simplex pattern recognition (5,10) with initialization conditions determined by a preliminary linear learning machine analysis (1,5) was carried out using between 290 and 300 member training sets composed of equal numbers of class and non-class spectra. For simplex computations, the Fisher ratio feature selection method was used (5), selecting those features possessing the 128 largest Fisher ratios for each category.…”

“…As a result, a number of such techniques have been the subject of recent investigation by both ourselves and others. These methods fall into the three broad categories of: parametric methods (which, in general, have relied on the development of linear additivity parameters) (14-19); heuristic methods (1)(2)(3)(4)20); and the use of similarity measures (of which, we consider spectral search systems to be one example) (12,14,21). The present results bear on the relative efficacy of learning machine (heuristic) interpretation of spectra as opposed to use of empirical peak occurrence probabilities for structural characterization via either Bayes or maximum likelihood classifiers.…”

Determination of anomeric configuration of D-ribofuranosyl nucleosides from nuclear magnetic resonance spectra by a pattern recognition technique

“…Even the dependence of the constants on the nature of the substituents in nucleosides as well as theoretical predictions do not prevent this application (4). A pattern recognition technique was recently applied to various kinds of structural problems based on different data collections, e.g., mass (5, 6), IR (7-9), NMR (10)(11)(12) spectra, search for possible anticancer drugs (13), etc.…”