This article describes a new algorithm for charge state determination and deconvolution of electrospray ionization (ESI) mass-to-charge ratio spectra. The algorithm (ZSCORE) is based on a charge scoring scheme that incorporates all above-threshold members of a family of charge states or isotopic components, and deconvolves both low- and high-resolution mass-to-charge ratio spectra, with or without a peak list (stick plot). A scoring weight factor, log (I/I0), in which I is the signal magnitude at a calculated mass-to-charge ratio, and I0 is the signal threshold near that mass-to-charge ratio, was used in most cases. For high-resolution mass-to-charge ratio spectra in which all isotopic peaks are resolved, the algorithm can deconvolve overlapped isotopic multiplets of the same or different charge state. Compared to other deconvolution techniques, the algorithm is robust, rapid, and fully automated (i.e., no user input during the deconvolution process). It eliminates artifact peaks without introducing peak distortions. Its performance is demonstrated for experimental ESI Fourier transform ion cyclotron resonance mass-to-charge ratio spectra (both low and high resolution). Charge state deconvolution to yield a "zero-charge" mass spectrum should prove particularly useful for interpreting spectra of complex mixtures, identifying contaminants, noncovalent adducts, fragments (N-terminal, C-terminal, internal), and chemical modifications of electrosprayed biomacromolecules.

Mass spectrometry-based de novo peptide sequencing is generally more reliable on high-resolution instruments owing to their high resolution and mass accuracy. On a lower resolution instrument such as the more widely used quadrupole ion traps, de novo peptide sequencing is not so reliable or requires more MS(3) experiments. However, the peptide CID spectrum has been demonstrated to be quite reproducible on an ion trap instrument and can be predicted with good accuracy. A new de novo peptide sequencing technique, DACSIM, combining a divide-and-conquer algorithm for deriving sequence candidates and spectrum simulation for sequence refinement, is developed for spectra acquired on an ion trap instrument. When DACSIM was used to sequence peptides 500-1900 u in mass generated from proteolytic digests of hemoglobin and myoglobin, the success rate was 70% with a false positive rate of only 6%, when isoleucine and leucine residues were not distinguished.

Withdrawal from a single exposure to ethanol produces transient but significant anxiety-like behavior, and repeated intermittent bouts of intoxication result in a significant extension of the duration of effect. The rapid emergence and progression of negative emotional signs of withdrawal may be a significant factor in determining susceptibility to transition from casual drinking to loss of control and escalating patterns of consumption that result in alcoholism.