TY - JOUR
T1 - Small-angle X-ray scattering studies of the manganese stabilizing subunit in photosystem II
AU - Svensson, Bengt
AU - Tiede, David M.
AU - Barry, Bridgette A.
PY - 2002/8/29
Y1 - 2002/8/29
N2 - Small-angle X-ray scattering studies (SAXS) were used to determine the size, shape, and oligomeric composition of the manganese stabilizing protein (MSP) of photosystem II. This extrinsic protein subunit plays an important role in photosynthetic oxygen evolution. As its name implies, MSP stabilizes the tetranuclear Mn cluster of the water oxidation complex. Removal of MSP lowers activity and decreases the stability of active-site manganese. Reconstitution of MSP reverses these effects. In this study, MSP was extracted from spinach PSII membranes using CaCl2 or urea. Through the use of MALDI-TOF mass spectrometry, the molecular weight of MSP was determined to be 26.53 kDa. X-ray scattering results show that both samples display a monodisperse scattering pattern; this pattern is consistent with a homogeneous protein solution. The CaCl2 extracted and urea extracted MSP samples have radii of gyration of 25.9 ± 0.4 and 27.0 ± 0.01 Å, respectively. MSP is shown to be monomeric in solution. This was determined using a cytochrome c standard and the scattering intensity, extrapolated to zero scattering angle, which is proportional to the molecular weight. This SAXS study suggests that, in solution, MSP is a monomeric, elongated prolate ellipsoid with dimensions, 112 × 23 × 23 Å3 and an axial ratio of 4.8.
AB - Small-angle X-ray scattering studies (SAXS) were used to determine the size, shape, and oligomeric composition of the manganese stabilizing protein (MSP) of photosystem II. This extrinsic protein subunit plays an important role in photosynthetic oxygen evolution. As its name implies, MSP stabilizes the tetranuclear Mn cluster of the water oxidation complex. Removal of MSP lowers activity and decreases the stability of active-site manganese. Reconstitution of MSP reverses these effects. In this study, MSP was extracted from spinach PSII membranes using CaCl2 or urea. Through the use of MALDI-TOF mass spectrometry, the molecular weight of MSP was determined to be 26.53 kDa. X-ray scattering results show that both samples display a monodisperse scattering pattern; this pattern is consistent with a homogeneous protein solution. The CaCl2 extracted and urea extracted MSP samples have radii of gyration of 25.9 ± 0.4 and 27.0 ± 0.01 Å, respectively. MSP is shown to be monomeric in solution. This was determined using a cytochrome c standard and the scattering intensity, extrapolated to zero scattering angle, which is proportional to the molecular weight. This SAXS study suggests that, in solution, MSP is a monomeric, elongated prolate ellipsoid with dimensions, 112 × 23 × 23 Å3 and an axial ratio of 4.8.
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U2 - 10.1021/jp0258199
DO - 10.1021/jp0258199
M3 - Article
AN - SCOPUS:0037194924
SN - 1089-5647
VL - 106
SP - 8485
EP - 8488
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 34
ER -