Chemistry Reference
In-Depth Information
7
Identii cation of Carotenoids
in Photosynthetic Proteins:
Xanthophylls of the Light
Harvesting Antenna
Alexander V. Ruban
CONTENTS
7.1 Introduction to Xanthophylls: Occurrence and Molecular Structure................................... 114
7.2 Analytical Approaches to Identii cation and Quantii cation of Xanthophylls:
Principles and Challenges..................................................................................................... 114
7.3 Localization and Functions of Xanthophylls in Light Harvesting Antenna of Plants ......... 117
7.3.1 The Need for Photosynthetic Antenna ..................................................................... 117
7.3.2 Structure of the Photosystem II Antenna: Xanthophylls in LHCII Structure .......... 117
7.3.3 Functions of Xanthophylls in the Antenna: A Structural Perspective ..................... 118
7.3.4 The Need for Identii cation of Xanthophylls
In Vivo ...............................................
119
7.4 Principles of Identii cation of Xanthophylls
In Vivo ............................................................
119
7.5 Identii cation of Xanthophylls Associated with the Transmembrane Helixes of
LHCII Antenna Complex: Neoxanthin and Lutein .............................................................. 121
7.5.1 Identii cation of Neoxanthin: The 9-
cis
Requirement for a Xanthophyll in the
C-Helix Domain ....................................................................................................... 122
7.5.2 Discovery of the Two Optically Different Luteins in LHCII ................................... 123
7.5.3 Identii cation of the Chlorophyll Excitation Quencher in Aggregated LHCII ......... 124
7.6 Distinguishing Coni gurational Variations in Xanthophylls ................................................ 125
7.6.1 Lutein 2 Twisting Coni guration in Trimeric LHCII................................................ 125
7.6.2 Neoxanthin Distortion upon Aggregation and Crystallization of LHCII
and
In Vivo................................................................................................................
126
7.7 Identii cation of Peripheral Xanthophylls: The Xanthophyll Cycle ..................................... 127
7.7.1 Principles of Identii cation of the Xanthophyll Cycle Carotenoids .......................... 128
7.7.2 Fingerprints of Interaction of the Peripheral Xanthophylls with Antenna
Proteins ..................................................................................................................... 128
7.8 Identii cation of Activated Zeaxanthin in the Photoprotective State of Antenna................. 130
7.9 Molecular Origins of the Resonance Raman Twisting Modes of
Antenna Xanthophylls .......................................................................................................... 131
7.10 Concluding Remarks ............................................................................................................ 132
7.10.1 Summary .................................................................................................................. 132
7.10.2 Future Directions ...................................................................................................... 133
References ...................................................................................................................................... 133
113
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