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Long-term storage of surface-adsorbed protein machines.

Albet-Torres N, Månsson A - Langmuir (2011)

Bottom Line: The effective and simple long-term storage of complex functional proteins is critical in achieving commercially viable biosensors.Importantly, therefore, we here describe that delicate heavy meromyosin (HMM)-based nanodevices (HMM motor fragments adsorbed to silanized surfaces and actin bound to HMM) fully maintain their function when stored at -20 °C for more than a month.The results are important to the future commercial implementation of motor-based nanodevices and are of more general value to the long-term storage of any protein-based bionanodevice.

View Article: PubMed Central - PubMed

Affiliation: School of Natural Sciences, Linnaeus University, SE-39245 Kalmar, Sweden. nuria.albettorres@lnu.se

ABSTRACT
The effective and simple long-term storage of complex functional proteins is critical in achieving commercially viable biosensors. This issue is particularly challenging in recently proposed types of nanobiosensors, where molecular-motor-driven transportation substitutes microfluidics and forms the basis for novel detection schemes. Importantly, therefore, we here describe that delicate heavy meromyosin (HMM)-based nanodevices (HMM motor fragments adsorbed to silanized surfaces and actin bound to HMM) fully maintain their function when stored at -20 °C for more than a month. The mechanisms for the excellent preservation of acto-HMM motor function upon repeated freeze-thaw cycles are discussed. The results are important to the future commercial implementation of motor-based nanodevices and are of more general value to the long-term storage of any protein-based bionanodevice.

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Effect of in vitro motility assay incubation conditions on motility quality after storage. (A) Flow cells frozen for 6 days. (B) Flow cells frozen for 30 days. In both A and B, the flow cells were subjected to only one freeze–thaw cycle. Bars show the velocity data (smooth bars) and the fraction of motile filaments (striped bars) of five different flow cells treated in different ways (shown in the x axes; see the text for a further explanation). Bright bars show data for the control flow cells (day 0), and dark bars show data after the freeze–thaw cycle. Error bars: SEM. Numbers in parentheses give the number of filaments from which the average sliding velocity was obtained by automatic tracking. One criterion for inclusion in the analysis was a coefficient of variation of the frame-to-frame velocity of <0.2. (See the text.) The fraction of motile filaments with error bars was obtained by observing three different areas of the flow cell.
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fig3: Effect of in vitro motility assay incubation conditions on motility quality after storage. (A) Flow cells frozen for 6 days. (B) Flow cells frozen for 30 days. In both A and B, the flow cells were subjected to only one freeze–thaw cycle. Bars show the velocity data (smooth bars) and the fraction of motile filaments (striped bars) of five different flow cells treated in different ways (shown in the x axes; see the text for a further explanation). Bright bars show data for the control flow cells (day 0), and dark bars show data after the freeze–thaw cycle. Error bars: SEM. Numbers in parentheses give the number of filaments from which the average sliding velocity was obtained by automatic tracking. One criterion for inclusion in the analysis was a coefficient of variation of the frame-to-frame velocity of <0.2. (See the text.) The fraction of motile filaments with error bars was obtained by observing three different areas of the flow cell.

Mentions: The HMM-propelled actin filament motility was maintained after the freezing and thawing of whole flow cells that contained all of the components of the IVMA (Experimental Section). When the flow cell had been frozen with both actin filaments and an ATP-containing assay solution and stored at −20 °C for up to 30 days, motility was resumed after thawing without the addition of new assay solution. This is exemplified in Figure 1A–C (Supporting Information, Movie 2). However, for quantitative comparison to the prefreezing conditions, it was important to avoid complications attributed to photobleaching, the consumption of ATP, and the accumulation of possible toxic products (e.g., gluconic acid due to the antibleaching mixture) during the first observation in the fluorescence microscope (before freezing). We therefore added a new assay solution and new actin filaments prior to quantitative measurements (Figure 1C). It can be seen in Figure 2 that both the sliding velocity and the fraction of motile filaments were similar to the values before freezing (no significant difference; p = 0.08 (velocity), p = 0.13 (fraction motile)). Data from different experiments was pooled in a single diagram because there was no apparent difference between flow cells kept frozen for different time periods (up to 30 days). Thus, motility was maintained for more than 1 month of freezing without a noticeable decay over this time period (Figures 3 and 4). In contrast to what was reported for lyophilization and critical-point drying(20) and subsequent reconstitution of the kinesin–microtubule motility assays, we did not observe any appreciable freeze–thaw-induced variability in function between different regions of a flow cell. Because we did not test lyophilization or other drying methods, these approaches might not be ideal for actomyosin (cf. ref (24)).


Long-term storage of surface-adsorbed protein machines.

Albet-Torres N, Månsson A - Langmuir (2011)

Effect of in vitro motility assay incubation conditions on motility quality after storage. (A) Flow cells frozen for 6 days. (B) Flow cells frozen for 30 days. In both A and B, the flow cells were subjected to only one freeze–thaw cycle. Bars show the velocity data (smooth bars) and the fraction of motile filaments (striped bars) of five different flow cells treated in different ways (shown in the x axes; see the text for a further explanation). Bright bars show data for the control flow cells (day 0), and dark bars show data after the freeze–thaw cycle. Error bars: SEM. Numbers in parentheses give the number of filaments from which the average sliding velocity was obtained by automatic tracking. One criterion for inclusion in the analysis was a coefficient of variation of the frame-to-frame velocity of <0.2. (See the text.) The fraction of motile filaments with error bars was obtained by observing three different areas of the flow cell.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3104519&req=5

fig3: Effect of in vitro motility assay incubation conditions on motility quality after storage. (A) Flow cells frozen for 6 days. (B) Flow cells frozen for 30 days. In both A and B, the flow cells were subjected to only one freeze–thaw cycle. Bars show the velocity data (smooth bars) and the fraction of motile filaments (striped bars) of five different flow cells treated in different ways (shown in the x axes; see the text for a further explanation). Bright bars show data for the control flow cells (day 0), and dark bars show data after the freeze–thaw cycle. Error bars: SEM. Numbers in parentheses give the number of filaments from which the average sliding velocity was obtained by automatic tracking. One criterion for inclusion in the analysis was a coefficient of variation of the frame-to-frame velocity of <0.2. (See the text.) The fraction of motile filaments with error bars was obtained by observing three different areas of the flow cell.
Mentions: The HMM-propelled actin filament motility was maintained after the freezing and thawing of whole flow cells that contained all of the components of the IVMA (Experimental Section). When the flow cell had been frozen with both actin filaments and an ATP-containing assay solution and stored at −20 °C for up to 30 days, motility was resumed after thawing without the addition of new assay solution. This is exemplified in Figure 1A–C (Supporting Information, Movie 2). However, for quantitative comparison to the prefreezing conditions, it was important to avoid complications attributed to photobleaching, the consumption of ATP, and the accumulation of possible toxic products (e.g., gluconic acid due to the antibleaching mixture) during the first observation in the fluorescence microscope (before freezing). We therefore added a new assay solution and new actin filaments prior to quantitative measurements (Figure 1C). It can be seen in Figure 2 that both the sliding velocity and the fraction of motile filaments were similar to the values before freezing (no significant difference; p = 0.08 (velocity), p = 0.13 (fraction motile)). Data from different experiments was pooled in a single diagram because there was no apparent difference between flow cells kept frozen for different time periods (up to 30 days). Thus, motility was maintained for more than 1 month of freezing without a noticeable decay over this time period (Figures 3 and 4). In contrast to what was reported for lyophilization and critical-point drying(20) and subsequent reconstitution of the kinesin–microtubule motility assays, we did not observe any appreciable freeze–thaw-induced variability in function between different regions of a flow cell. Because we did not test lyophilization or other drying methods, these approaches might not be ideal for actomyosin (cf. ref (24)).

Bottom Line: The effective and simple long-term storage of complex functional proteins is critical in achieving commercially viable biosensors.Importantly, therefore, we here describe that delicate heavy meromyosin (HMM)-based nanodevices (HMM motor fragments adsorbed to silanized surfaces and actin bound to HMM) fully maintain their function when stored at -20 °C for more than a month.The results are important to the future commercial implementation of motor-based nanodevices and are of more general value to the long-term storage of any protein-based bionanodevice.

View Article: PubMed Central - PubMed

Affiliation: School of Natural Sciences, Linnaeus University, SE-39245 Kalmar, Sweden. nuria.albettorres@lnu.se

ABSTRACT
The effective and simple long-term storage of complex functional proteins is critical in achieving commercially viable biosensors. This issue is particularly challenging in recently proposed types of nanobiosensors, where molecular-motor-driven transportation substitutes microfluidics and forms the basis for novel detection schemes. Importantly, therefore, we here describe that delicate heavy meromyosin (HMM)-based nanodevices (HMM motor fragments adsorbed to silanized surfaces and actin bound to HMM) fully maintain their function when stored at -20 °C for more than a month. The mechanisms for the excellent preservation of acto-HMM motor function upon repeated freeze-thaw cycles are discussed. The results are important to the future commercial implementation of motor-based nanodevices and are of more general value to the long-term storage of any protein-based bionanodevice.

Show MeSH
Related in: MedlinePlus