Photosynthesis Research

, Volume 9, Issue 1, pp 3–12

Molecular arrangement of pigment-protein complex of photosystem 1

Authors

  • V. V. Shubin
    • A.N. Bakh Institute of BiochemistryUSSR Academy of Sciences
  • N. V. Karapetyan
    • A.N. Bakh Institute of BiochemistryUSSR Academy of Sciences
  • A. A. Krasnovsky
    • A.N. Bakh Institute of BiochemistryUSSR Academy of Sciences
Antennae

DOI: 10.1007/BF00029726

Cite this article as:
Shubin, V.V., Karapetyan, N.V. & Krasnovsky, A.A. Photosynth Res (1986) 9: 3. doi:10.1007/BF00029726

Abstract

The circular dichroism (CD) method was applied to study the molecular organization of P700, antenna chlorophyll and protein of photosystem 1 complexes (CP1), isolated from chloroplasts under mild treatment with Triton X-100. Analysis of CD spectra and protein: chlorophyll: P700 ratios for CP1 complexes that were different in their chlorophyll content indicate that CP1 preparations can be considered as a mixture of CP1-RC, containing P700 (10–20%), and CP1-LH without P700 (80–90%). Both types of complexes contain approximately 25 chlorophyll molecules, and the destruction of their spatial organization with detergents represents a cooperative transition. The rate of chlorophyll destruction in CP1-LH is much higher than that in CP1-RC. In both complexes a 65 kDa polypeptide predominates, whose secondary structure (typical for α/β proteins) is stable to Triton X-100 and does not depends on the chlorophyll content. Chlorophyll seems to be grouped in clusters (5–7 molecules) in the hydrophobic cores of 2–3 parallel α/β domains of the 65 kDa protein. Only one of the clusters in CP1-RC includes P700; on P700 photooxidation the change of its interaction with the nearest pigment environment results in a complicated shape of the light-induced CD spectra.

Key words

light-harvesting complex (pea)cPIIoptical absorptionlinear dichroismchroismprotein secondary structure

Abbreviations

PS1

photosystem 1

CP1

pigment-protein complex of PS1

Chl

chlorophyll a

CP1-140

CP1 with ratio Ch1:P700 140

RC

reaction center

LH

light-harvesting pigment

CP1-RC

CP1, containing P700

CP1-LH

CP1 without P700 (containing LH)

CD

circular dichroism

SDS

sodium dodecyl sulfate

Copyright information

© Martinus Nijhoff/Dr. W. Junk Publishers 1986