Prof. Hu Kaifeng from Kunming Institute of Botany visited WIPM

On August 16th, 2012, Prof. Hu Kaifeng from Kunming Institute of Botany, Chinese Academy of Sciences (CAS), was invited by Prof. Tang Huiru to visit Wuhan Institute of Physica and Mathematic (WIPM, CAS), and had delivered an excellent report entitled “Simultaneous quantification and identification of individual chemicals in metabolite mixtures by two-dimensional extrapolated time-zero 1H-13C HSQC (HSQC0)”.
In the report, Prof. Hu described in detail that quantitative one-dimensional 1H NMR spectroscopy is a useful tool for determining metabolite concentrations because of the direct proportionality of signal intensity to the quantity of analyte. However, severe signal overlapping in 1D 1H NMR spectra of complex metabolite mixtures hinders accurate quantification. Extension of 1D 1H to 2D 1H-13C HSQC leads to the dispersion of peaks along the 13C dimension and greatly alleviates peak overlapping. Although peaks are better resolved in 2D 1H-13C HSQC than in 1D 1H NMR spectra, the simple proportionality of cross peaks to the quantity of individual metabolites is lost by resonance-specific signal attenuation during the coherence transfer periods. He showed here that data from series of HSQC spectra acquired with incremented repetition times (the time between the end of the first 1H excitation pulse to the beginning of data acquisition) can be extrapolated back to zero time to yield a time-zero 2D 1H-13C HSQC spectrum (HSQC0) in which signal intensities are proportional to concentrations of individual metabolites. Clustering of the HSQC0 cross peaks by their normalized intensities identifies those corresponding to metabolites present at a given concentration, and this information can assist in assigning these peaks to specific compounds. Further, He combined gradient-selective time-zero 1H-13C HSQC0 with fast maximum likelihood reconstruction (FMLR) data analysis and the use of two concentration references for absolute concentration determination. Semi-automatic data analysis is supported by the FMLR approach, which is used to deconvolute the spectra and extract peak volumes. The peak volumes obtained from this analysis are converted to absolute concentrations by reference to the peak volumes of two internal reference compounds of known concentration. For bovine liver extract samples, 47 regions of interest (ROI) were chosen for simultaneous quantification of 23 metabolites in the mixture. He expected that this approach can be used to quantify other natural products of interest in extracts without prior purification.
At the end of the report, Prof. Hu carried out productive communication and discussion with research staff and students. Later, he visited the experimental platform of metabonomics, amazed by the development of our institute. And he hoped in-depth exchange.
Prof. Hu Kaifeng got his undergraduate degree in pharmaceutical sciences from Beijing Medical University (Beijing University), graduated with an MA in natural products chemistry from Shanghai Institute of Materia Medica, CAS, and obtained his PhD from Eidgenössische Technische Hochschule Zürich (ETH). His post-doctoral research was on NMR and was carried out at Laboratory of Chemical Physics, NIDDK, National Institutes of Health, USA. Current research activities are to develop new methods of NMR and applications of NMR and LC-MS to quantitative metabolomics.