scholarly journals Unusual reactivity of Tyr-7 of GSH transferase P1-1

1993 ◽  
Vol 293 (2) ◽  
pp. 351-356 ◽  
Author(s):  
D J Meyer ◽  
C Xia ◽  
B Coles ◽  
H Chen ◽  
P Reinemer ◽  
...  
Keyword(s):  
Chemical Reactivity ◽  
Three Dimensional ◽  
Covalent Modification ◽  
Proton Acceptor ◽  
Dimensional Structure ◽  
Second Derivative ◽  
Tyrosine Residue ◽  
Derivative Spectra ◽  
Activity Sequence ◽  
Second Derivative Spectra

Reaction of human GSH transferase P1-1 (GSTP1-1) with diethylpyrocarbonate (DEPC) at pH 7.0 and 4 degrees C resulted in covalent modification of an equivalent of one histidine and one tyrosine residue per subunit, with loss of activity. Sequence analysis showed that His-71 and Tyr-7 were modified. Reference to the three-dimensional structure of GSTP1-1 [Reinemer, Dirr, Ladenstein, Huber, Lo Bello, Frederici and Parker (1992) J. Mol. Biol. 227, 214-226] shows that the modification of Tyr-7 is most likely to affect enzyme activity. Kinetic analysis of the DEPC modification of Tyr-7 in GSTP1-1 gave a k2 approx. 150 times that of a peptide comprising residues 1-11 of GSTP1-1. The reaction of Tyr-7 of GSTP1-1 with DEPC was poorly inhibited by 1 mM GSH (14%) or 10 microM S-hexylglutathione (18%). DEPC treatment of the enzyme altered the absorbance at 290 nm in second-derivative spectra, suggesting that a significant amount of tyrosinate ion occurs in the enzyme. GSH, however, did not significantly alter the A290. The data provide the first evidence of unusual chemical reactivity of Tyr-7 and are consistent with its proposed role as a proton acceptor during catalysis.

Second‐Derivative Spectra for Estimating Crop Residue Cover

1994 ◽  
Vol 86 (2) ◽  
pp. 349-354 ◽  
Author(s):  
Haiping Su ◽  
Michel D. Ransom ◽  
Edward T. Kanemasu ◽  
Tanvir H. Demetriades‐Shah
Keyword(s):  
Crop Residue ◽  
Second Derivative ◽  
Derivative Spectra ◽  
Second Derivative Spectra

Multi-wavelength analyses of second-derivative spectra for rapid determination of acetaminophen in serum.

1988 ◽  
Vol 34 (6) ◽  
pp. 1119-1121 ◽  
Author(s):  
B Dingeon ◽  
M A Charvin ◽  
M T Quenard ◽  
H Thome
Keyword(s):  
Phosphate Buffer ◽  
Rapid Determination ◽  
Turnaround Time ◽  
Second Derivative ◽  
Derivative Spectra ◽  
Multi Wavelength ◽  
Precision And Accuracy ◽  
Second Derivative Spectra ◽  
Method Of Extraction

Abstract Measurement of acetaminophen by analysis of the second derivative of its spectrum is specific and sensitive. The method of extraction and the use of just one phosphate buffer as reagent makes this method very convenient. Readings are reliable from 10 to 1500 mg/L. A turnaround time of 20 min makes this method well suited for emergency cases. Precision and accuracy of the method are presented. Results are not biased by interferences, not even from N-acetylcysteine.

Approach for Increased Information from the Second-Derivative Spectra in UV-Vis Absorption Spectroscopy

1993 ◽  
Vol 47 (10) ◽  
pp. 1712-1715 ◽  
Author(s):  
Liudmil Antonov ◽  
Stefan Stoyanov
Keyword(s):  
Absorption Spectra ◽  
Wavelength Region ◽  
Second Derivative ◽  
Holographic Gratings ◽  
Long Wavelength ◽  
Derivative Spectra ◽  
Individual Bands ◽  
Basic Parameters ◽  
Computing Procedure ◽  
Second Derivative Spectra

The resolution of overlapping bands in the UV-Vis absorption spectra leading to determination of their basic parameters ([Formula: see text]) provides important information about the energies and probabilities of the electronic transitions. In the analysis of UV-Vis absorption spectra recorded linearly in wavelength by means of modern spectrophotometers with holographic gratings, the analytical shape describing individual bands is asymmetric. This factor leads to certain limitations in determining their number with the use of the second-derivative spectra and decreased effectiveness of the computing procedure. It was found that the loss of information in d2 A/dλ2 is due to its long-wavelength attenuation in comparison with d2 A/dν˜2. An analytical equation connecting d2 A/dλ2 with d2 A/dν˜2 is proposed, which restores the information from the second derivative in the long-wavelength region.

scholarly journals Life Experience and DNA Polymorphisms Influence the Brain Epigenome

2013 ◽  
Vol 40 (5) ◽  
pp. 726-727
Author(s):  
Michael O. Poulter
Keyword(s):  
Life Experience ◽  
Cancer Susceptibility ◽  
Methylation Status ◽  
Three Dimensional ◽  
Covalent Modification ◽  
Dna Polymorphisms ◽  
Dimensional Structure ◽  
Fetal Alcohol ◽  
Wide Range ◽  
Biological Outcomes

Although not strictly fitting the category of translational neuroscience, I believe the implications of this study where it was found that variability in DNA sequence, a single nucleotide polymorphism (SNP), can influence the epigenetic status of DNA and this is influenced by childhood trauma should be of wide interest.Epigenetics is a burgeoning field of study that seeks to understand how alterations in DNA structure influence a wide range of biological outcomes ranging from cancer susceptibility to behaviour. Across this spectrum, two basic kinds of structure are most often examined. The first is covalent modification of DNA by methylation and second is the interaction between DNA binding proteins (histones for example) and DNA. Both influence the three dimensional structure of DNA and therefore gene expression. Importantly these dynamics are thought to be influenced by environmental conditions that may be positive or detrimental. For example, fetal alcohol syndrome has been shown to alter the methylation status of DNA accounting for the facial/cranial abnormalities that are often observed in these patients.

scholarly journals NIR Absorbance Characteristics of Deoxynivalenol and of Sound and Fusarium-Damaged Wheat Kernels

2009 ◽  
Vol 17 (4) ◽  
pp. 213-221 ◽  
Author(s):  
Kamaranga H.S. Peiris ◽  
Michael O. Pumphrey ◽  
Floyd E. Dowell
Keyword(s):  
Absorption Spectra ◽  
Near Infrared ◽  
Peak Height ◽  
Second Derivative ◽  
Absorption Bands ◽  
Derivative Spectra ◽  
Nir Absorption ◽  
Second Derivative Spectra ◽  
Food Reserves ◽  
Wheat Kernels

The near infrared (NIR) absorption spectra of deoxynivalenol (DON) and single wheat kernels with or without DON were examined. The NIR absorption spectra of 0.5–2000 ppm of DON in acetonitrile were recorded in the 350–2500 nm range. Second derivative processing of the NIR spectra and spectral subtractions showed DON absorption bands at 1408 nm, 1904 nm and 1919 nm. NIR spectra of sound and Fusarium-damaged kernels were also acquired using two instruments. Subtraction of average absorption spectra and second derivative spectra were evaluated to identify different NIR signatures of the two types of kernel. Differences in peak height and positions of the NIR absorption bands of the kernels were noted. At 1204 nm, 1365 nm and 1700 nm, the differences were in the heights of the absorption peaks. Such differences may be attributed to changes in the levels of grain food reserves such as starches, proteins and lipids and other structural compounds. Shifts in absorption peak positions between the two types of kernels were observed at 1425–1440 nm and 1915–1930 nm. These differences may arise from other NIR active compounds, such as DON, which are not common for the two types of kernel. Since the NIR absorption of DON may have contributed to the shifts between sound and Fusarium-damaged kernels, this study indicates the potential for NIR spectrometry to evaluate Fusarium damage in single kernels based on the DON levels.

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