The Influence of NBS
Modification of 241Trp on the Reconstitution of 33 kD Protein
with PSⅡand on the Recovery of Oxygen-evolving Activity
YU Yong, LI Rong, TIAN Shao-Min1, XU Chun-He*
and RUAN Kang-Chen1
( Shanghai Institute of Plant Physiology, the Chinese Academy of Sciences,
Shanghai 200032, China;1Shanghai Institute of
Biochemistry, the Chinese Academy of Sciences, Shanghai 200031, China
)
Abstract The extrinsic 33 kD protein of
photosystemⅡ(PSⅡ) plays an important role in the stabilizing of manganese
cluster and maintaining high oxygen-evolving activity of PSⅡ. In this research,
241Trp, the only tryptophan in the 33 kD protein, was modified by
N-Bromosuccinimide. The pH-dependence of modification suggests that this
tryptophan is buried in the hydrophobic interior of the protein. The protein’s
capability of reconstitution to the PSⅡdecreased after modification, and no
oxygen-evolving activity of PSⅡwas recovered after the reconstitution. Results
suggest that 241Trp of the 33 kD protein is essential for the
binding of the protein to the PSⅡand the normal oxygen-evolving activity.
Key Words 33 kD protein； tryptophan； chemical modification； PSⅡ； oxygen evolution
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