：
Hiroshi Tsugawa
Email: hiroshi.tsugawa@riken.jp
Affiliation: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku,
Yokohama, Kanagawa, 230-0045, Japan
We developed new software program, MRMPROBS, for widely targeted metabolomics.
Widely targeted metabolomics is one of the metabolomics approaches based on the “large scale” multiple (selected) reaction monitoring by means of triple quadrupole mass spectrometer. This strategy became increasingly popular for the simultaneous analysis of up to several hundred metabolites at high sensitivity, selectivity, and quantitative capability.
In order to easily handle the large MRM data sets, two important issues should be solved in the software.

The user friendly graphical user interface to easily allow data curation.

The objective evaluation system to accurately get the target metabolite from the complicated chromatograms.
Recently, we overcame these requirements and provided the MRMPROBS software. (Figure 1)

Figure 1: Screen shot of MRMPROBS
This software, the manual, and the example files are freely available from our RIKEN website.
( http://prime.psc.riken.jp
: Follow a link: “Targeted and Non-targeted analysis software” ->
“MRMPROBS”) The researchers can get an organized data matrix for statistical analysis easily and quickly by means of MRMPROBS. Moreover, this program also implements a probabilistic scoring system for each peak detected from the MRM chromatograms.
It evaluates the metabolite peaks by posterior probability, defined as the odds ratio by means of a newly optimized multivariate logistic regression model. The predictors consist of five variables (Figure 2):
1.
Peak intensity
2.
Retention time similarity
3.
Amplitude ratio similarity between the target transition and the qualifier transition
4.
Peak top differential similarity of a peak group
5.
Peak shape similarity of a peak group

Figure 2. Variables summary
These predictors are integrated in MRMPROBS program and the novel scoring system enabled us to filter not only noise peaks but also isomeric metabolite peaks without label compounds. Importantly, the objective criterion facilitates the meaningful and useful assessment of identification results.
Because the software supports all data processing method from raw data import to the construction of data matrix (Actually, some statistical analyses are also available in MRMPROBS), it is a useful and practical tool for the assessment of large-scale MRM data sets.
Recently, Microsoft Excel based statistical analysis platform is released for further statistical analyses such as principal component analysis (PCA) and projection to latent structure based multivariate analysis (PLS-R, PLS-DA)(Figure 3). Although the MRMPROBS software provides the useful platform to construct a data matrix, it is also very important to provide the statistical analysis platform for metabolomics study. To easily re-arrange the figures or tables of statistical results, we provides the excel macro platform in RIKEN PRIMe web site. ( http://prime.psc.riken.jp
: Follow a link: “Targeted and Non-targeted analysis software” -> “Tool for statistical analysis on Microsoft
Excel”)

Figure 3. Overview of the excel based statistical analysis platform
Nodaway, the metabolomics technique has been frequently performed in many research fields owing to very excellent platforms which include not only data analysis platform but also the sample preparation, the metabolite extraction method and analytical method. However, we have to develop more useful and more innovative techniques to spread metabolomics all over the world.
Of course, MRMPROBS is still being improved for the researcher’s needs. We will offer the practical metabolomics techniques including data processing method as well as the analytical method.
Reference
Tsugawa et al. MRMPROBS: A Data Assessment and Metabolite Identification Tool for Large-Scale
Multiple Reaction Monitoring Based Widely Targeted Metabolomics Analytical Chemistry , 85,
5191-5199, 2013