It is important to identify non-planar deformations of porphyrin macrocycle in metallo-porphyrin proteins due to their functional relevance. The relationship between non-planar deformations of porphyrin macrocycle and low frequency Raman spectral bands of Ni(II) meso-tetraphenyl porphyrin (NiTPP), with different coordination numbers, was studied by density functional theory (DFT), normal coordinate structural decomposition method and Raman experiments. The results show that the crystal of four-coordinate NiTPP has two major kinds of non-planar deformations: ruffling and saddling. The non-planar deformations of ruffling and saddling for NiTPP are 1.473 Å and 0.493 Å determined by DFT calculation. The ruffling and saddling deformations can be identified by using the low frequency Raman characteristic peaks ( γ 12 , γ 13 ) and ( γ 16 , γ 17 ), respectively. When four-coordinate NiTPP is transformed to the six-coordinate bis(pyrrolidine) NiTPP (NiTPP(Pyr) 2 ), the large non-planar distortion of the porphyrin macrocycle almost disappears, with the non-planar deformation of saddling only about 0.213 Å estimated by DFT calculation. Experimentally, we can make use of the characteristic peaks of low frequency Raman spectra to identify the saddling deformation beyond 0.25 Å.
Yanbin Su,Xuwei Sun,Ruixue Wu,Xing Zhang,Yunzhou Tu
The purpose of this study was to explore the molecular spectroscopic behaviors of the beta-arbutin on the toxic aldehyde of trans-crotonaldehyde in anti-skin cancer. Results revealed that both hydroxymethyl and phenolic hydroxyl of beta-arbutin led to the shift of the maximum ultraviolet peak of trans-crotonaldehyde from a very significant absorption peak at 300 nm to a very weak absorption peak at 310 nm and the significant shift of the aldehyde Raman band at 1689/cm of the toxic trans-crotonaldehyde in mitochondria and aldehyde dehydrogenase, respectively. The beta-arbutin acting on the toxic trans-crotonaldehyde highlighted the potential of anti-skin cancer and provided a valuable clue for the new application of the beta-arbutin.
Olaniyi Oladipo Oladiti,Yang Kai,Zhu Yong-Guan,Cui Li
Biodegradation of cellulose-rich substrates is an indispensable process for soil carbon replenishment in various ecological niches. Biodegradation of cellulose has been studied extensively via an enzyme assay to quantify the amount of cellulase with a view to identify effective cellulose degraders. However, a bulk enzyme assay undermines the role of physiological heterogeneity between cells; it is therefore imperative to opt out for a more effective method such as single-cell Raman spectroscopy combined with heavy water (D 2 O) to reveal active cellulose degraders. Cellular incorporation of D 2 O-derived D produces a new C-D Raman band which can act as a quantitative indicator of microbial activity. In this study, metabolic responses of seven cellulose-degrading bacteria to carboxymethylcellulose (CMC) and glucose were evaluated via the C-D Raman band. On the basis of % C-D, CMC was demonstrated to be most efficiently metabolized by Bacillus velezensis 2a-9 and Providencia vermicola 5a-9(b). Metabolic activity between individual cells of B . velezensis and P . vermicola towards CMC ranged from approximately 8 to 27% and 6 to 16%, respectively, clearly indicating heterogeneous degradation activities among isogenic populations. Linear correlation between % C-D and specific endoglucanase activity validated Raman results on CMC-degrading activity. Also, % C-D obtained from bacteria cultivated with only glucose was around 60% higher than that obtained from CMC, indicating the preference of bacteria for simple sugar glucose than CMC. In conclusion, Raman spectroscopy combined with heavy water is a sensitive analytical technique to reveal cellulose degraders and their degrading activities.
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