Issue 24, 2009

Sequential processing from cell lysis to protein assay on a chip enabling the optimization of an F1-ATPase single molecule assay condition

Abstract

We developed an integrated protein assay device, “Single Molecule MicroTAS (SMM),” which enables cell lysis, protein extraction, purification, and activity assay. The assay was achieved at the single-molecule scale for a genetically engineered protein, F1-ATPase, which is the smallest known rotary motor. A cell lysis condition, with a wide range of applied voltages (50–250 V) and other optimized values (pulse width: 50 µs; duty: 0.01%; electrode gap: 25 µm; total flow rate: 5 µL min−1) provided a high enough protein concentration for the assay. Successively, the protein was extracted and purified by specific binding in a microfluidic channel. During the assay process, the diffusion effect of lysate between a two-phase laminar flow contributes to optimizing the single-molecule assay condition, because the concentration of the original lysate from the E. coli solution is too high to assay. To achieve the most efficient assay condition, the protein diffusion effect on the assay was experimentally and numerically evaluated. The results reveal that, in our experimental conditions, concentrations of F1 and other contaminated effluents are optimized for the F1 rotational assay at a channel position. The adenosine triphosphate (ATP)-driven rotation speed measured in the SMM was compatible with that obtained by conventional purification and assay. Such a sequential process from cell lysis to assay proves that the SMM is an example of a sample-in-answer-out system for F1protein evaluation.

Graphical abstract: Sequential processing from cell lysis to protein assay on a chip enabling the optimization of an F1-ATPase single molecule assay condition

Supplementary files

Article information

Article type
Paper
Submitted
09 Jun 2009
Accepted
14 Sep 2009
First published
13 Oct 2009

Lab Chip, 2009,9, 3567-3573

Sequential processing from cell lysis to protein assay on a chip enabling the optimization of an F1-ATPase single molecule assay condition

T. Nakayama, M. Namura, K. V. Tabata, H. Noji and R. Yokokawa, Lab Chip, 2009, 9, 3567 DOI: 10.1039/B911148D

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