Introduction
Large biomolecules when ionized by electrospray (ESI) are predominantly multiply charged. When analyzed in the positive ion mode, peptides or proteins will be protonated at multiple sites as a result of the basic amino acids and amino terminus. An example ESI mass spectrum of human growth hormone is shown in the figure below.
On the other hand, oligonucleotides analyzed in the negative ion mode are de-protonated at multiple sites as a result of the acidic phosphate backbone. The multiple charging of biomolecules usually results in ESI mass spectra that contain a range of possible charge states. These complex spectra must be "deconvoluted" or "transformed" in order to order to determine the uncharged mass of the biomolecule. ProMass provides an automated platform for performing deconvolution of entire LC/MS data sets. An example of a ProMass deconvoluted human growth hormone spectrum is shown below.
Overview
ProMass for Xcalibur is an automated biomolecule deconvolution and reporting software package that is used to process ESI/LC/MS data or single ESI mass spectra acquired with the Finnigan Xcalibur data system. ProMass uses a novel deconvolution algorithm known as ZNova that produces artifact-free deconvoluted mass spectra. ZNova can be used to process data from a wide variety of biomolecules including proteins, oligonucleotides, peptides, etc. Unlike many other deconvolution algorithms, ZNova can accomodate low charge state spectra and data of low signal-to-noise ratio. ProMass processing can be initiated through the Xcalibur Sequence Setup view, which allows the user to run a list of samples and have ProMass process them automatically. ProMass reports the results automatically in an easy-to-use and interactive format viewable from any web browser. A ProMass Browser summary page collates the results from multiple runs and displays them on a single hyperlinked page allowing you to navigate your results quickly. Target mass features allow you to search for multiple target masses from LC/MS data automatically. The target mass features include results color coding, allowing you to quickly determine which samples require immediate attention.
