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| Title: Comparison of three spectrophotometric methods for the determination of gamma-oryzanol in rice bran oil .
| | Author: Bucci R MagrEAD MagrEAL Marini F | | Journal: Citation: V : 375 ( 8 ) P : 1254-9 Year: 2003 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub12733048 Accession (PMID): 12733048 | | Abstract: A comparison of the results obtained by applying three spectrophotometric methods ( at fixed wavelength , second-derivative and multicomponent analysis ) to the determination of gamma-oryzanol in rice bran oil is reported . At fixed wavelength the results are more accurate when using isopropyl alcohol , rather than n-heptane , to dilute the oil samples , because the absorption bands of gamma-oryzanol are red-shifted and the absorbance , measured at lambda ( max ) =327 nm , is less affected by the interference of the oil "matrix" ( lambda ( max ) =314 nm in n-heptane ) . However , to obtain accurate results also in oils with a low content of gamma-oryzanol , it is necessary to perform the analysis using second-derivative ( ( 2 ) D330 . 365 ) or multicomponent ( lambda=310-360 nm ) methods .
The first one fully removes the interference of oil matrix whilst the second , which needs a specific computational program to process the spectrophotometric data , furnishes evidence the presence of some unexpected interference in the analysis and/or standards which are not representative of the analysed samples , from the square root of the sum of the squared differences at each point between the linear combination of the standards and the unknown spectra ( RMS error ) . Finally , some aspects of the chemical , spectroscopic ( UV , IR ) and thermoanalytical ( TG , DSC ) behaviour of gamma-oryzanol and the values of the parameters which enable "computation" of its UV spectra are reported .
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[ Sen. 1, subscore: 1.00 ]: A comparison of the results obtained by applying three spectrophotometric methods ( at fixed wavelength , second-derivative and multicomponent analysis ) to the determination of gamma-oryzanol in rice bran oil is reported . At fixed wavelength the results are more accurate when using isopropyl alcohol , rather than n-heptane , to dilute the oil samples , because the absorption bands of gamma-oryzanol are red-shifted and the absorbance , measured at lambda ( max ) =327 nm , is less affected by the interference of the oil "matrix" ( lambda ( max ) =314 nm in n-heptane ) . However , to obtain accurate results also in oils with a low content of gamma-oryzanol , it is necessary to perform the analysis using second-derivative ( ( 2 ) D330 . 365 ) or multicomponent ( lambda=310-360 nm ) methods .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
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| Title: Functionally important amino acids in rice sucrose transporter OsSUT1 .
| | Author: Sun Y Lin Z Reinders A Ward JM | | Journal: Biochemistry Citation: V : 51 P : 3284-91 Year: 2012 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub22458969 Accession (PMID): 22458969 | | Abstract: Six conserved , charged amino acids within membrane spans in rice sucrose transporter OsSUT1 were identified using a three-dimensional structural model based on the crystal structures of three major facilitator superfamily ( MFS ) proteins : LacY , GlpT , and EmrD .
These positions in OsSUT1 were selected for mutagenesis and biochemical assays .
Among the six mutants , D177N completely lost transport function , D331N retained only a small fraction of sucrose uptake activity ( 2 . 3% of that of the wild type ) , and R335H and E336Q also displayed a substantial decrease in transport activity .
D329N functioned as well as wild-type OsSUT1 .
R188K did not transport sucrose but showed a H ( + ) leak that was inhibited by sucrose , indicating that R188K had uncoupled sucrose and H ( + ) translocation .
This demonstrates that charged amino acids within membrane spans are important for the transport mechanism of OsSUT1 as they are in lactose permease .
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[ Sen. 3, subscore: 1.00 ]: Among the six mutants , D177N completely lost transport function , D331N retained only a small fraction of sucrose uptake activity ( 2 . 3% of that of the wild type ) , and R335H and E336Q also displayed a substantial decrease in transport activity .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
