시험 관내 분석에서 포스파티딜 메틸화 된 역가를 측정하는 방법
Summary
The present report describes an in vitro enzymatic assay to measure phosphatidylethanolamine methyltransferase activity using Leishmania cell extracts. This assay is based on the transfer of a radioactive methyl group from S-[Methyl-3H]adenosyl-L-methionine onto endogenous phosphatidylethanolamine.
Abstract
Phosphatidylethanolamine methyltransferases are biosynthetic enzymes that catalyze the transfer of one or more methyl group(s) from S-adenosyl-L-methionine onto phosphatidylethanolamine, monomethyl-phosphatidylethanolamine, or dimethyl-phosphatidylethanolamine to give either monomethyl-phosphatidylethanolamine, dimethyl-phosphatidylethanolamine or phosphatidylcholine. These enzymes are ubiquitous in animal cells, fungi, and are also found in approximately 10% of bacteria. They fulfill various important functions in cell physiology beyond their direct role in lipid metabolism such as in insulin resistance, diabetes, atherosclerosis, cell growth, or virulence. The present manuscript reports on a simple cell-free enzymatic assay that measures the transfer of tritiated methyl group(s) from S-[Methyl-3H]adenosyl-L-methionine onto phosphatidylethanolamine using whole cell extracts as an enzyme source. The resulting methylated forms of phosphatidylethanolamine are hydrophobic and thus, can be separated from water soluble S-[Methyl-3H]adenosyl-L-methionine by organic extraction. This assay can potentially be applied to any other cell types and used to test inhibitors/drugs specific to a phosphatidylethanolamine methyltransferase of interest without the need to purify the enzyme.
Introduction
포스파티딜 에탄올 아민의 메틸화 된은 (PEMT) 효소 모노-PE, 디메틸 PE 및 / 또는 제공하기 위해 PE, 모노 – PE 또는 디메틸 PE 상 메틸기 공여체로서 S의 -adenosylmethionine (SAM)을 사용하여 하나 이상의 메틸 그룹의 공유 결합을 촉진 포스파티딜콜린 (PC). 이 효소는 동물 세포와 곰팡이에 거의 어디에나 있습니다. 이들은 또한 몇몇 식물 1 세균의 약 10 %, 진핵 2와 상호 작용하는, 특히에서 찾을 수있다.
PEMTs이뿐만 아니라, 다른 중요한 세포 기능을 다함으로써 동물 세포에서 주요 지질 클래스 PC의 생산에 기여함으로써 세포 생물학에 적합하다. 포유류에서 PEMTs 주로 그들은 매우 저밀도 지질 단백질의 정상적인 분비에 필요한 간에서 발현되며, 또한식이 유도 비만 (3), 동맥 경화증 (4)에 기여하고, 인슐린 저항ANCE 5. 또한, 포유류 PEMT은 비록 낮은 수준으로, 지방 세포에서 발현, 지방 침착 (6, 7)에 참여하고 있습니다. 암 발생 8, 9 사멸 및 세포 증식 10 PEMT 역할도 입증되었다. 박테리아, PEMT 효소는 숙주 식물 (11)와 정상 세포 성장 2, 2 병독성과 공생 중요한 것으로 밝혀졌다.
본 프로토콜의 목적 및 근거는 효소를 정제 할 필요없이 전체 세포 추출물로부터 PEMT 활성을 측정하는 방법이다. 두 가지 프로토콜 PEMT 활성을 측정하기 위해 개발되었다. 첫 번째 가장 일반적인 하나는이 문서의 주제 PE, 상 방사성 SAM에서 삼중 메틸 그룹의 전송을 측정한다. 이 프로토콜은 원래 underst을 얻기 위해 효모 및 포유 동물 세포 (12) (간) (13)로부터 PEMT 활성을 측정하기 위해 개발되어왔다이들 세포에서 PC 생합성 AND 작업뿐만 아니라 이들 효소의 특이성을 결정한다. 나중에,이 기술 및 원생 동물 기생충 14 (15 비록 분석 용 염기성 pH 값을 이용하여) (2) 박테리아와 같은 다른 세포 유형에 적용되고있다. 이 기술은 전체 세포 추출물뿐만 아니라, 정제 된 효소로 사용할 수 있고, 잠재적으로 모든 세포 추출물 시스템에 적용 할 수있다. 비 방사성 분석도의 S -adenosylhomocysteine, SAM (16)의 transmethylation 생성물의 정량 효소에 의존하는 설계되었다. 이 방사능을 포함하지 않는 한 후자의 분석은 더 편리 할 수 있지만 정제 효소에만 적합합니다.
Protocol
Representative Results
Discussion
이 단순한 빠른 PEMT 분석은 단백질 원으로 전체 세포 추출액을 이용하여 PE 상 SAM에서 방사성 메틸기의 전달로 인한 PE의 메틸화 된 형태의 정량을 허용한다. 그것은 빠르고, 민감한, 재현성, 정제 효소 17도 적합하다. 관심 메틸화 된 오히려 PE 12,13,18,19보다 이들 기판에 특정한 경우 Monomethyl- 또는 디메틸 PE는 상기 분석에 첨가 될 수있다. 정제 PEMT 효소가 사용되는 경우, PE는 분석에 …
Disclosures
The authors have nothing to disclose.
Acknowledgements
This work was supported by NIH grants ARRA RO3 AI078145 and 1SC3GM113743 to RZ.
Materials
| S-[Methyl-3H]adenosyl-L-methionine (specific activity of 5-15 Ci/mMole) | Perkin Elmer | NET155050UC | Aliquot the reagent and freeze at -20 °C; follow radiation safety guidelines while using this reagent |
| Protease inhibitor cocktail | Roche Life Sciences | 11836170001 | dilute it fresh |
| Glass beads, acid washed, 425-600 mm | Sigma Aldrich | G8772 | |
| Bicinchoninic acid solution | Sigma Aldrich | B9643 | |
| Copper (II) sulfate | Sigma Aldrich | C2284 | |
| Scintillation counter MicroBeta2 with 1-detector | Perkin Elmer | 2450-0010 | |
| Spectrophotometer Biomate 3 | Thermo Scientific | 840208300 | |
| BSA stock solution (10 mg/ml) | New England Biolabs | B9001S | |
| Scintillation liquid | Research Product International Corp | 111198 | |
| S-(5'-Adenosyl)-L-methionine chloride (hydrochloride) | Cayman Chemicals | 13956 | dilute the reagent in 20 mM HCl and freeze aliquots at -80 °C |
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