Near-infrared spectroscopy （NIRS） with its fast and nondestructive advantages can be qualified for the real-time quantitative analysis. This paper demonstrates that NIRS combined with partial least squares （PLS） r...Near-infrared spectroscopy （NIRS） with its fast and nondestructive advantages can be qualified for the real-time quantitative analysis. This paper demonstrates that NIRS combined with partial least squares （PLS） regression can be used as a rapid analytical method to simultaneously quantify L-glutamic acid （L- GIu） and γ-aminobutyric acid （GABA） in a biotransformation process and to guide the optimization of production conditions when the merits of NIRS are combined with response surface methodology. The high performance liquid chromatography （HPLC） reference analysis was performed by the o-phthaldialdehyde pre-column derivatization. NIRS measurements of two batches of 141 samples were firstly analyzed by PLS with several spectral pre-processing methods. Compared with those of the HPLC reference analysis, the resulting determination coefficients （R2）, root mean square error of prediction （RMSEP） and residual predictive deviation （RPD） of the external validation for the L-GIu concentration were 99.5%, 1.62 g/L, and 11.3, respectively. For the GABA concentration, R2, RMSEP, and RPD were 99.8%, 4.00 g/L, and 16.4, respectively. This NIRS model was then used to optimize the biotransformation process through a Box- Behnken experimental design. Under the optimal conditions without pH adjustment, 200 gjL L-GIu could be catalyzed by 7148 U/L glutamate decarboxylase （GAD） to GABA, reaching 99% conversion at the fifth hour. NIRS analysis provided timely information on the conversion from L-GIu to GABA. The results suggest that the NIRS model can not only be used for the routine profiling of enzymatic conversion, providing a simple and effective method of monitoring the biotransformation process of GABA, but also be considered to be an optimal tool to guide the optimization of production conditions.展开更多
An efficient and facile method to reduce nitriles to amine-boranes was developed.Aromatic and aliphatic nitriles were readily reduced in the presence of both sodium amidoborane(NaAB)and LiBH4 at room temperature in TH...An efficient and facile method to reduce nitriles to amine-boranes was developed.Aromatic and aliphatic nitriles were readily reduced in the presence of both sodium amidoborane(NaAB)and LiBH4 at room temperature in THF without catalysts,affording products in up to 99%yield.The products can be easily hydrolyzed to afford primary amines or utilized as reducing reagents for one-pot reductive amination.The key finding of the reaction study is the synergy effect between NaAB and LiBH4;otherwise the reaction yield would drop substantially from 92%to 22%or 12%when NaAB and LiBH4 are used separately.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 81374046 and 81373506)
文摘Near-infrared spectroscopy （NIRS） with its fast and nondestructive advantages can be qualified for the real-time quantitative analysis. This paper demonstrates that NIRS combined with partial least squares （PLS） regression can be used as a rapid analytical method to simultaneously quantify L-glutamic acid （L- GIu） and γ-aminobutyric acid （GABA） in a biotransformation process and to guide the optimization of production conditions when the merits of NIRS are combined with response surface methodology. The high performance liquid chromatography （HPLC） reference analysis was performed by the o-phthaldialdehyde pre-column derivatization. NIRS measurements of two batches of 141 samples were firstly analyzed by PLS with several spectral pre-processing methods. Compared with those of the HPLC reference analysis, the resulting determination coefficients （R2）, root mean square error of prediction （RMSEP） and residual predictive deviation （RPD） of the external validation for the L-GIu concentration were 99.5%, 1.62 g/L, and 11.3, respectively. For the GABA concentration, R2, RMSEP, and RPD were 99.8%, 4.00 g/L, and 16.4, respectively. This NIRS model was then used to optimize the biotransformation process through a Box- Behnken experimental design. Under the optimal conditions without pH adjustment, 200 gjL L-GIu could be catalyzed by 7148 U/L glutamate decarboxylase （GAD） to GABA, reaching 99% conversion at the fifth hour. NIRS analysis provided timely information on the conversion from L-GIu to GABA. The results suggest that the NIRS model can not only be used for the routine profiling of enzymatic conversion, providing a simple and effective method of monitoring the biotransformation process of GABA, but also be considered to be an optimal tool to guide the optimization of production conditions.
基金We are grateful to the National Natural Science Foundation of China(No.22171246,22101261,21771057,and U1804253)Zhengzhou University of China for the financial support of this research.
文摘An efficient and facile method to reduce nitriles to amine-boranes was developed.Aromatic and aliphatic nitriles were readily reduced in the presence of both sodium amidoborane(NaAB)and LiBH4 at room temperature in THF without catalysts,affording products in up to 99%yield.The products can be easily hydrolyzed to afford primary amines or utilized as reducing reagents for one-pot reductive amination.The key finding of the reaction study is the synergy effect between NaAB and LiBH4;otherwise the reaction yield would drop substantially from 92%to 22%or 12%when NaAB and LiBH4 are used separately.
