Name: Manually Extracting the Bradford Assay Data Recorded with a Smartphone
Uploaded: 2023-09-08T14:50:00
Description: Watch this Scientific Journal Video about Manually Extracting the Bradford Assay Data Recorded with a Smartphone at JoVE.com

manually extracting the bradford assay data recorded with a smartphone

Bradford Assayを使用してタンパク質を定量する分析デバイスとしてのスマートフォン

Regardless of the downstream use (e.g., ELISA, enzyme kinetics, western blotting, protein purification, and mass spectrometry), protein quantification is crucial for accurate analysis in life sciences laboratories. In addition to their use as secondary readouts (i.e., to calculate relative levels of analytes per mass of protein), protein levels in a sample can also be the desired output itself. For example, one can be interested in protein levels in food resources1 or in urine2. There are many methods available to measure protein concentration in samples3, including direct UV absorbance readings4, protein-copper chelation5,6, protein-dye binding colorimetric assays7, and protein-dye binding fluorescent assays8. The relevance of protein quantitation is evidenced by the presence of two papers describing protein measurement methods5,7 in the top-3 of the most cited literature9,10. Despite the fact that many authors neglect their actual citation by citing non-primary references or not citing anything at all, the original papers describing the Lowry protein assay and the Bradford protein assay amount &#62;200,000 citations each10.
The popularity of the Bradford assay stems from its affordability, simplicity, speed, and sensitivity. The assay is based on the interaction between proteins and the dye Coomassie Brilliant Blue G under acidic conditions. Under the conditions of the assay (i.e., low pH), the dye exists in three forms: a red cationic form with &#955;max at 470 nm; a green neutral form with &#955;max at 650 nm; and a blue anionic form with &#955;max at 590 nm11,12 (Figure 1). The cationic form predominates in the absence of proteins. As proteins interact with the dye, they stabilize the blue anionic form, causing a noticeable change in the color of the solution, from brownish to blue. Usually, the change in the concentration of the blue form of the dye is quantified spectrophotometrically, whose absorbance at 590-595 nm is proportional to the quantity of protein in the assay.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/65547/65547fig01v2.jpg" /> 
Figure 1: Coomassie brilliant blue G absorption spectra under the conditions of the Bradford assay. The three main peaks are marked with arrows indicating the &#955;max of the red (470 nm), green (650 nm), and blue (590 nm) forms of the dye. Spectra were recorded in the absence of protein (yellow line) and in the presence of 3 &#181;g (gray line) and 10 &#181;g (blue line) of bovine serum albumin. <a href="https://www.jove.com/files/ftp_upload/65547/65547fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
The widespread use of the Bradford assay has led to the identification of several limitations (e.g., variable responses to different proteins11, and interference by lipids13 and detergents7) and the development of modifications to improve its performance (e.g., the addition of detergents14,15, alkalinization14,16 and use of the ratio of absorbances17). In addition to modifications in the assay itself, the use of alternative devices, such as smartphones or cameras, to capture analytical signals have also been described18,19,20. Indeed, the development of methods that make use of smartphones as portable chemical analyzers has been an active area of research. The motivation for the use of smartphones stems from the affordability, portability, ease of use, and widespread availability of these devices.
This paper provides a protocol for protein quantification using the RGBradford assay20, which uses a smartphone as an analytical device. In contrast to the original RGBradford publication20, here, a procedure that streamlines the color extraction process has been introduced. It involves the utilization of a freely available software application to extract color information from each well of a microplate picture automatically, saving significant time and effort. This is an alternative to the previous method of manually acquiring color data from each well one by one using a graphics editor software application20. Ultimately, protein levels in samples can be quantified using color data extracted from a picture of a microplate taken with a smartphone.

著者スポットライト:スマートフォンを使用したBradford Assayによるタンパク質定量への代替アプローチ(英語) 

RGBradford:スマートフォンカメラによるタンパク質定量(英語)

Our research focuses on understanding at the biochemical level how animals adapt to extreme environmental conditions. We explore questions about their response to lack of oxygen and suppression of metabolic rate. Specifically, we investigate endogenous antioxidants, oxidative stress, and cellularity stress response animals employ in a adverse environment.And to do so, we often quantify protein levels in our samples. This protocol addresses the need for an alternative method to obtain protein quantification data when resource are limited, making it a valuable tool in both educational and research contexts. The RG Bradford Assay offers a practical and reliable solution for protein concentration measurement that is accessible, simple, and accurate in scenarios where conventional equipment such as a microplate reader may be unavailable.

Watch this Scientific Journal Video about Manually Extracting the Bradford Assay Data Recorded with a Smartphone at JoVE.com

Manually Extracting the Bradford Assay Data Recorded with a Smartphone  

スマートフォンで記録したブラッドフォードアッセイデータの手動抽出

スマートフォンのカメラで撮影したマイクロプレートの画像からブラッドフォードアッセイのデータを手動で抽出するには、無料のオープンソースグラフィックエディタであるInkscapeをダウンロードしてください。Inkscapeを開き、ファイルに移動して、「開く」をクリックして、スマートフォンを使用して撮影したマイクロプレートの写真を選択します。左上に矢印で表示されているオブジェクトの選択と変形ツールを選択し、画像をクリックします。破線の境界線は、選択を示します。次に、左側にスポイトとして描かれている画像Dツールから色を選択を選択します。次に、ウェルの中央をクリックします。それに応じて、下部パネルの色である塗りつぶしが変わります。色をクリックすると、右側に塗りつぶしとストロークのタブがポップアップ表示されます。フラットカラーのドロップダウンメニューをRGBに変更します。各ウェルの青と緑のチャンネルに表示された値を記録します。記録された値を使用して、青と緑の比率を計算します。

Research

JoVE Journal

Biochemistry

Manually Extracting the Bradford Assay Data Recorded with a Smartphone

RGBradford: Protein Quantitation with a Smartphone Camera

Protein quantitation is an essential procedure in life sciences research. Amongst several other methods, the Bradford assay is one of the most used. ...