opa assay for accurate glutathione detection in cells

GSH/GSSG 측정 – 항산화 연구를 위한 정제된 OPA 분석

Reactive oxygen species (ROS) are a primary inducer of oxidative stress; oxidative stress has been well established in the generation of DNA mutations, cellular aging/ death, various cancers, diabetes, neurological diseases (such as Parkinson&#39;s and Alzheimers), and several other life-debilitating conditions1,2,3,4,5. A key defense against ROS are thiolic, non-enzymatic antioxidants, which are capable of reducing oxidants or radicals by acting as proton donors6,7. Glutathione (GSH) and cysteine are the two most prevalent thiols found in mammals8, while various other low molecular weight thiols exist (such as ergothioneine), GSH and cysteine are the most commonly measured non-enzymatic antioxidants found in literature9,10,11 and hold greatest relevance for combatting ROS8,12,13,14.
When GSH is utilized as an antioxidant, two molecules of GSH are covalently linked together via a disulfide bond to make glutathione disulfide (GSSG). Depletion of GSH is often used as an indicator of oxidative stress15,16. This assessment can also be combined with the detection of GSSG, although increases in GSSG in cells are often limited by active export processes since GSSG can be relatively reactive in cells, leading to disulfide bond formation with other protein thiols16.
Traditional methods for measuring GSH and GSSG are not simple processes and require numerous steps, including cellular extraction using lytic reagents17,18. The protocol outlined here simplifies these methods and allows the accurate measurement of non-enzymatic thiols and normalization using the cellular protein content or adenylate kinase release. In addition, it is possible to measure cellular viability prior to GSH/GSSG extraction. Several methods have previously attempted to target and quantify reduced and oxidized non-enzymatic thiols efficiently; methods including the use of HPLC19,20,21, plate assay (biochemical)22,23,24,25, and which use common reagents for thiol conjugation, such as 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB/ Ellman&#39;s reagent)19, Monochlorobimane (mBCI)26,27,28. Several companies have also prepared proprietary kits for the detection of glutathione; however, they do not publish reagent incompatibilities, which presents issues dependent on the treatments used29.
This protocol outlines a multiparametric assay that detects reduced thiols (such as GSH) via ortho-phthalaldehyde (OPA) conjugation to produce a fluorescent signal detectable at 340/450 Ex/Em, respectively. This assay facilitates the detection of both GSH and GSSG simultaneously (in plate), through the use of masking agents (N-ethylmaleimide) and GSSG reducing agents (tris(2-carboxyethyl) phosphine). This multi-biomarker protocol also provides an opportunity during the cellular lysing stage to quantify proteins via bicinchoninic acid assay for the normalization of samples on completion of the final measurement or via an adenylate kinase assay from the cell media. This assay can be performed utilizing several reagents readily available in most laboratories and only requires a few additional uncommon chemicals to perform. The process is simple, accessible, and can be performed without laborious stages in less than 2 h.
In this protocol, various nanomaterials were chosen that were either previously shown to induce ROS or suspected to induce oxidative stress30,31. A concentration range was explored to see the effects of exposure of these nanomaterials on various cell lines and the effectiveness of the assay in quantifying antioxidant thiols.

저자 스포트라이트: 산화 스트레스 연구를 위한 혁신적인 티올 정량화 및 바이오마커 검출 

In vitro에서 배양된 포유류 세포에서 ortho -phthaldehyde를 사용한 산화 및 환원 형태의 글루타치온의 신속한 정량화

We aim to offer a novel means to quantify thiol concentration with a specific focus on the GSH and GSSG concentrations of the various cell lines that can be performed in situ. We consider this a useful protocol for the scientific community. Numerous efforts have been made to detect niche and specific biomarkers of interest of reactive oxygen species, and several have found great interest in detecting short-lived reactive oxygen species, such as radical detection and small molecules such as hydroxyls and singlet oxygen.One key challenge for several institutions has been the ability to accurately and specifically detect biomarkers of interest without the need of expensive equipment or laborious processes. This protocol allows for multiparametric analysis, allowing for normalization of data without the need for separate protocols, and remove several stages found in other assays that are highly time consumptive, present incompatible reagents, or use reagents hazardous to health. The Nanomaterial Safety Group will continue to assess various nanomaterials and polymers for the effect they may have on human health.We consider this protocol an essential part of our toolkit in achieving this goal as this protocol can potentially be multiplexed to detect additional biomarkers.

세포에서 정확한 글루타치온 검출을 위한 OPA 분석

시작하려면 분석에 필요한 모든 재료를 준비합니다. GSH 표준물질의 경우, 각 웰에 40마이크로리터의 총 글루타치온 완충액을 첨가합니다. 다음으로, 세포 펠릿이 들어있는 플레이트의 각 웰에서 배지를 흡인하고 얼음처럼 차가운 PBS로 세포를 세 번 세척합니다.10 마이크로리터의 글루타치온과 이중 증류수를 블랭크로 삼중 분할하여 보정 범위를 준비합니다. 원하는 표적 정량화를 위해 세척된 세포를 적절한 혼합물과 함께 300RPM의 오비탈 셰이커에서 2분 동안 배양합니다. 그런 다음 0.01 몰 트리스, 2- 카르복시 에틸 포스 핀 용액 5 마이크로 리터를 각 웰에 넣고 10 분 동안 다시 배양합니다.다음으로, 플레이트를 200G에서 5분 동안 원심분리하고 단백질 정량을 위해 각 샘플 웰에서 25마이크로리터를 별도의 투명 96웰 플레이트로 옮깁니다. 그런 다음 170마이크로리터의 작동하는 오르토프탈알데히드 용액을 30마이크로리터의 샘플이 들어 있는 각 웰에 추가합니다. 플레이트를 빛으로부터 보호하려면 호일로 철저히 덮고 궤도 셰이커에서 15분 동안 배양합니다.마지막으로, 플레이트 리더를 사용하여 340나노미터 여기 및 450나노미터 방출에서 형광을 판독합니다. 다양한 나노물질로 처리된 A549 세포는 이 분석에서 서로 다른 글루타치온 이황화 비율을 보였으며 은 밀리리터당 125마이크로그램으로 처리된 세포에서 가장 높은 값이 관찰되었습니다.

opa-assay-for-accurate-glutathione-detection-in-cells

Research

JoVE Journal

Biochemistry

OPA Assay for Accurate Glutathione Detection in Cells

326 조회수.  Teesside University. 시작하려면 분석에 필요한 모든 재료를 준비합니다. GSH 표준물질의 경우, 각 웰에 40마이크로리터의 총 글루타치온 완충액을 첨가합니다. 다음으로, 세포 펠릿이 들어있는 플레이트의 각 웰에서 배지를 흡인하고 얼음처럼 차가운 PBS로 세포를 세 번 세척합니다.10 마이크로리터의 글루타치온과 이중 증류수를 블랭크로 삼중 분할하여 보정 범위를 준비합니다. 원하는 표?...

비디오: 세포에서 정확한 글루타치온 검출을 위한 OPA 분석

Rapid Quantification of Oxidized and Reduced Forms of Glutathione Using Ortho -phthalaldehyde in Cultured Mammalian Cells In Vitro

Glutathione has long been considered a key biomarker for determining the antioxidant response of the cell. Hence, it is a primary marker for reactive oxygen species studies. The method utilizes Ortho-phthalaldehyde (OPA) to quantify the cellular concentration of glutathione(s). OPA conjugates with reduced glutathione (GSH) via sulfhydryl binding to subsequently form an isoindole, resulting in a highly fluorescent conjugate. To attain an accurate result of both oxidized glutathione (GSSG) and GSH, a combination of masking agents and reducing agents, which have been implemented in this protocol, are required. Treatments may also impact cellular viability. Hence, normalization via protein assay is presented in this multiparametric assay. The assay demonstrates a pseudo-linear detection range of 0.234 - 30&#181;M (R2=0.9932&#177;0.007 (N=12)) specific to GSH. The proposed assay also allows for the determination of oxidized glutathione with the addition of the masking agent N-ethylmaleimide to bind reduced glutathione, and the reducing agent tris(2-carboxyethyl) phosphine is introduced to cleave the disulfide bond in GSSG to produce two molecules of GSH. The assay is used in combination with a validated bicinchoninic acid assay for protein quantification and an adenylate kinase assay for cytotoxicity assessment.

Quantification of both oxidized and reduced forms of glutathione (GSSG and GSH, respectively) has been achieved through the use of Ortho-phthalaldehyde (OPA). OPA becomes highly fluorescent once conjugated to GSH but is unable to conjugate GSSG until reduced. Here, we describe a multiparametric assay to quantify both using protein quantification for normalization.

Glutathione has long been considered a key biomarker for determining the antioxidant response of the cell. Hence, it is a primary marker for reactive ...