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Trypsination of inside‐out chloroplast thylakoid vesicles for localization of the water‐splitting site
Author(s) -
Jansson Christer,
Andersson Bertil,
Åkerlund Hans-Erik
Publication year - 1979
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(79)80912-6
Subject(s) - library science , chemistry , computer science
Many conflicting results have been reported concerning the location of the water splitting site in the chloroplast thylakoid membrane [ 1,2]. An internal location has been assumed mainly from the internal release of protons linked to oxygen production [3,4] and the selective release of manganese into the lumenal space upon Tris treatment [S]. In contrast, an external exposure has been inferred from the inactivation of photosystem II electron transport by chemical probes considered to be unable to penetrate the membrane [6,7]. A location at the outer surface has also been concluded from the trypsin digestion of the chloroplast lamellae [8,9] while the effect of trypsin has been claimed to be due mainly to proteolysis of the reducing side of photosystem II [lO,l I]. These conflicting results may reflect the inherent limitations in modifying only the outer membrane surface for studies on the transverse organization of a membrane. Modification of a component on the outer surface may cause rearrangements in the membrane which leads to inactivation of internal catalytic sites. However, the absence of effects does not reveal whether a component is located internally or just shielded behind some bulky membrane constituents. A direct comparison between the effects of non-penetrating reagents on the outer and inner membrane surfaces is therefore desirable. Such