title: Pure forms of the singlet oxygen sensors TEMP and TEMPD do not inhibit Photosystem II.
abstract: In a recent article (Hakala-Yatkin and Tyystjärvi BBA 1807 (2011) 243-250) it was reported that the singlet oxygen spin traps 2,2,6,6-tetramethylpiperidine (TEMP) and 2,2,6,6-tetramethyl-4-piperidone (TEMPD) inhibit Photosystem II (PSII), the water oxidizing enzyme. O₂ evolution, chlorophyll fluorescence and thermoluminescence were measured and were shown to be greatly affected by these chemicals. This work casts doubts over an earlier body of work in which these chemicals were used as spin traps for monitoring ¹O₂ production when PSII was inhibited by high light intensities. Here we show that these spin probes hardly affect PSII. We show that the commercial batches of TEMPD and TEMP used by Hakala-Yatkin and Tyystjärvi contained impurities and/or derivatives that inhibited PSII and caused the specific effects on fluorescence. Earlier work that used pure spin traps to measure ¹O₂ during photoinhibition, thus remains valid. However, concern must be expressed towards using these spin traps without proper controls.
authors: Institute of Plant Biology, Biological Research Center of the Hungarian Academy of Sciences, P.O. Box 521, 6701 Szeged, Hungary.
authors: Eva
authors: E
authors: Hideg
authors: Zsuzsanna
authors: Z
authors: Deák
authors: Marja
authors: M
authors: Hakala-Yatkin
authors: Maarit
authors: M
authors: Karonen
authors: A William
authors: AW
authors: Rutherford
authors: Esa
authors: E
authors: Tyystjärvi
authors: Imre
authors: I
authors: Vass
authors: Anja
authors: A
authors: Krieger-Liszkay
mesh_terms: D008027:Light; D045332:Photosystem II Protein Complex / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010880:Piperidines / Q000737:chemistry*; D010881:Piperidones / Q000737:chemistry*; D026082:Singlet Oxygen / Q000737:chemistry*; D013113:Spin Labels; D018724:Spinacia oleracea / Q000737:chemistry / Q000166:cytology; D020524:Thylakoids / Q000737:chemistry
chemical_list: D045332:Photosystem II Protein Complex; D010880:Piperidines; D010881:Piperidones; D013113:Spin Labels; D026082:Singlet Oxygen; C551336:2,2,6,6-tetramethylpiperidide