자질<em> 체외</em효소 특성에 대한> ATP 아제 활동
Summary
We describe a basic protocol for quantitating in vitro ATPase activity. This protocol can be optimized based on the level of activity and requirements for a given purified ATPase.
Abstract
아데노신 삼인산 가수 분해 효소, 또는 -ATPase를는 세포 기능의 다양한 배열에 중요한 역할을한다. 이러한 동적 단백질은 단백질 인신 매매 및 저하, 용질 수송, 및 세포의 움직임과 같은 기계적인 작업을위한 에너지를 생성 할 수 있습니다. 여기에 설명 된 프로토콜은 기능적 특성화 -ATPase를 정제의 시험 관내 활성을 측정하기위한 기본적인 분석이다. 단백질은 무기 포스페이트 방출을 초래 반응의 ATP 가수 분해 및 유리 된 인산의 양은 다음 비색 정량 분석법을 사용한다. 이것은 고도로 적응 프로토콜 운동 또는 엔드 포인트 분석에서 ATP 아제 활성을 측정하기 위해 조정될 수있다. 대표적인 프로토콜이 활동과 EPSE의 요구 사항에 따라 여기에 제공되면, AAA + ATP 아제는 박테리아 비브리오 콜레라를 입력 II 분비에 관여. 활성을 측정하기 위해 필요로 정제 된 단백질의 양을 분석의 길이와 SA의 타이밍 및 횟수mpling 간격, 버퍼 소금 조성, 온도, 공동 요인, 각성제 (있는 경우) 등이 여기에 설명하는 것과 다를 수 있습니다, 따라서 약간의 최적화가 필요할 수 있습니다. 이 프로토콜의 특성 -ATPase를위한 기본 틀을 제공하고 신속하게 수행하고 쉽게 필요한 조절 될 수있다.
Introduction
ATPases are integral enzymes in many processes across all kingdoms of life. ATPases act as molecular motors that use the energy of ATP hydrolysis to power such diverse reactions as protein trafficking, unfolding, and assembly; replication and transcription; cellular metabolism; muscle movement; cell motility; and ion pumping1-3. Some ATPases are transmembrane proteins involved in transporting solutes across membranes, others are cytoplasmic and may be associated with a biological membrane such as the plasma membrane or those of organelles.
AAA+ ATPases (ATPases associated with various cellular activities) make up a large group of ATPases that share some sequence and structural conservation. These proteins contain conserved nucleotide binding motifs such as Walker-A and -B boxes and form oligomers (generally hexamers) in their active state1. Large conformational changes in these proteins upon nucleotide binding have been characterized among diverse members of the AAA+ family. EpsE is a AAA+ ATPase and member of the bacterial Type II/IV secretion subfamily of NTPases4-6. EpsE powers Type II Secretion (T2S) in Vibrio cholerae, the causative agent of cholera. The T2S system is responsible for the secretion of a wide variety of proteins, such as the virulence factor cholera toxin that causes profuse watery diarrhea when V. cholerae colonizes the human small intestine7.
Techniques for quantitating in vitro ATPase activity are varied, but commonly measure phosphate release using colorimetric, fluorescent, or radioactive substrates8-11. We describe a basic method for determining in vitro ATPase activity of purified proteins using a colorimetric assay based on a commercially available malachite green-containing substrate that measures liberated inorganic phosphate (Pi). At low pH, malachite green molybdate forms a complex with Pi and the level of complex formation can be measured at 650 nm. This simple and sensitive assay may be used to functionally characterize new ATPases and to evaluate the roles of potential activators or inhibitors, to determine the importance of domains and/or specific residues, or to assess the effect of particular treatments on enzymatic activity.
Protocol
Representative Results
Discussion
이 생화학 적 특성에 대한 정제 된 단백질의 생체 외 ATP 아제 활동 측정하는 일반적인 프로토콜입니다. 이 방법은 쉽게 최적화되어 있습니다; 예를 들어, 단백질, 완충 염 및 조성물, 온도, 및 상기 분석과 다양한 길이 (간격의 총 개수를 증가 포함) 간격의 양을 조절하는 활성을 정량을 향상시킬 수있다. 시판 말라카이트 그린 기반의 시약은 매우 민감, 무료 인산 소량 검출 할 수있다 …
Disclosures
The authors have nothing to disclose.
Acknowledgements
The authors would like to acknowledge funding from a National Institutes of Health grant RO1AI049294 (to M. S.).
Materials
| HEPES buffer | Fisher | BP310-500 | |
| Sodium chloride | Fisher | BP358-212 | |
| Magnesium chloride | Fisher | BP214-500 | |
| Adenosine triphosphate (ATP) | Fisher | BP41325 | |
| 96-well plates (clear, flat-bottom) | VWR | 82050-760 | |
| BIOMOL Green | Enzo Life Sciences | BML-AK111 | Preferred phosphate detection reagent. Caution: irritant. |
| Microplate reader | BioTek Synergy or comparable | ||
| Prism 5 | GraphPad Software | ||
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