Limits...
Nonlinear dielectric spectroscopy as an indirect probe of metabolic activity in thylakoid membrane.

Fang J, Palanisami A, Rajapakshe K, Widger WR, Miller JH - Biosensors (Basel) (2011)

Bottom Line: Here we use the light-activated electron transport chain of spinach thylakoid membrane as a model system to study how NDS interacts with metabolic activity.We find protein modification, as opposed to membrane pump activity, to be the dominant source of NDS signal change in this system.Potential mechanisms for such protein modifications include reactive oxygen species generation and light-activated phosphorylation.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 77204, USA. jfang@mail.uh.edu.

ABSTRACT
Nonlinear dielectric spectroscopy (NDS) is a non-invasive probe of cellular metabolic activity with potential application in the development of whole-cell biosensors. However, the mechanism of NDS interaction with metabolic membrane proteins is poorly understood, partly due to the inherent complexity of single cell organisms. Here we use the light-activated electron transport chain of spinach thylakoid membrane as a model system to study how NDS interacts with metabolic activity. We find protein modification, as opposed to membrane pump activity, to be the dominant source of NDS signal change in this system. Potential mechanisms for such protein modifications include reactive oxygen species generation and light-activated phosphorylation.

No MeSH data available.


Related in: MedlinePlus

Measurement of the 2nd harmonic response with varying driving frequency. (a) 2nd harmonic response before (square) and immediately after (circle) a 2 min exposure to light. Both 2nd harmonic response measurements are taken in the dark, with each point the average of a 4 s acquisition and 8 Vpp driving voltage. (b) O2 concentration was recorded at all times. The time span of harmonic measurement is indicated by a box (before light application) and a circle (after light application). The measurement was carried out with 0.2 mg/mL chlorophyll in 5 mL suspension buffer with 1.0 mM K3Fe(CN)6 as described in the text.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4264345&req=5

biosensors-01-00013-f002: Measurement of the 2nd harmonic response with varying driving frequency. (a) 2nd harmonic response before (square) and immediately after (circle) a 2 min exposure to light. Both 2nd harmonic response measurements are taken in the dark, with each point the average of a 4 s acquisition and 8 Vpp driving voltage. (b) O2 concentration was recorded at all times. The time span of harmonic measurement is indicated by a box (before light application) and a circle (after light application). The measurement was carried out with 0.2 mg/mL chlorophyll in 5 mL suspension buffer with 1.0 mM K3Fe(CN)6 as described in the text.

Mentions: The harmonics produced by spinach thylakoid in response to AC electric fields at frequencies between 1 kHz and 10 kHz were examined at a fixed amplitude of 8 Vpp. Measurements in the dark were compared before and after a 2 min application of light (Figure 2(a)). As seen in Figure 2(a), the 2nd harmonic response decreases after light exposure. To confirm the photosynthetic activation of the ETC, the buffer oxygen concentration was measured simultaneously with the harmonic measurements (Figure 2(b)). The evolution of O2 is clear evidence of photosynthetic ETC activity.


Nonlinear dielectric spectroscopy as an indirect probe of metabolic activity in thylakoid membrane.

Fang J, Palanisami A, Rajapakshe K, Widger WR, Miller JH - Biosensors (Basel) (2011)

Measurement of the 2nd harmonic response with varying driving frequency. (a) 2nd harmonic response before (square) and immediately after (circle) a 2 min exposure to light. Both 2nd harmonic response measurements are taken in the dark, with each point the average of a 4 s acquisition and 8 Vpp driving voltage. (b) O2 concentration was recorded at all times. The time span of harmonic measurement is indicated by a box (before light application) and a circle (after light application). The measurement was carried out with 0.2 mg/mL chlorophyll in 5 mL suspension buffer with 1.0 mM K3Fe(CN)6 as described in the text.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4264345&req=5

biosensors-01-00013-f002: Measurement of the 2nd harmonic response with varying driving frequency. (a) 2nd harmonic response before (square) and immediately after (circle) a 2 min exposure to light. Both 2nd harmonic response measurements are taken in the dark, with each point the average of a 4 s acquisition and 8 Vpp driving voltage. (b) O2 concentration was recorded at all times. The time span of harmonic measurement is indicated by a box (before light application) and a circle (after light application). The measurement was carried out with 0.2 mg/mL chlorophyll in 5 mL suspension buffer with 1.0 mM K3Fe(CN)6 as described in the text.
Mentions: The harmonics produced by spinach thylakoid in response to AC electric fields at frequencies between 1 kHz and 10 kHz were examined at a fixed amplitude of 8 Vpp. Measurements in the dark were compared before and after a 2 min application of light (Figure 2(a)). As seen in Figure 2(a), the 2nd harmonic response decreases after light exposure. To confirm the photosynthetic activation of the ETC, the buffer oxygen concentration was measured simultaneously with the harmonic measurements (Figure 2(b)). The evolution of O2 is clear evidence of photosynthetic ETC activity.

Bottom Line: Here we use the light-activated electron transport chain of spinach thylakoid membrane as a model system to study how NDS interacts with metabolic activity.We find protein modification, as opposed to membrane pump activity, to be the dominant source of NDS signal change in this system.Potential mechanisms for such protein modifications include reactive oxygen species generation and light-activated phosphorylation.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 77204, USA. jfang@mail.uh.edu.

ABSTRACT
Nonlinear dielectric spectroscopy (NDS) is a non-invasive probe of cellular metabolic activity with potential application in the development of whole-cell biosensors. However, the mechanism of NDS interaction with metabolic membrane proteins is poorly understood, partly due to the inherent complexity of single cell organisms. Here we use the light-activated electron transport chain of spinach thylakoid membrane as a model system to study how NDS interacts with metabolic activity. We find protein modification, as opposed to membrane pump activity, to be the dominant source of NDS signal change in this system. Potential mechanisms for such protein modifications include reactive oxygen species generation and light-activated phosphorylation.

No MeSH data available.


Related in: MedlinePlus