Chapter 4
Crystal Nucleation of Proteins Induced
by Surface Plasmon Resonance
Tetsuo Okutsu
Abstract The crystallization of lysozyme and ribonucleaseA was induced using
photochemical reactions triggered by surface plasmon resonance of gold nanostructures. The tryptophan residues of the protein are radicalized by the enhanced electric field induced by surface plasmon resonance. This radical reacts in the protein
molecule to produce a reaction intermediate in which a nearby tyrosine residue is
radicalized. This reaction intermediate reacts with another protein to form a dimer
linked by tyrosine residues. Since this dimer is covalently bonded, it is stable without
decomposition. With this as a nucleus, it grows into a crystal. An enhanced electric
field induced by surface plasmon resonance of gold nanostructures was used to radicalize amino acids in proteins. Surface plasmon resonance induced by visible light
radicalizes amino acids by the same mechanism as multiphoton absorption. When
a metastable solution of lysozyme and ribonucleaseA was dropped on the substrate
on which the gold nanostructure was constructed, and surface plasmon resonance of
the gold nanostructure was induced, crystals precipitated.
Keywords Surface plasmon resonance · Protein crystallization · Lysozyme ·
RibonucleaseA · Gold nanostructure
4.1 Introduction
Experiments to crystallize proteins are important in the fields of drug discovery and
structural biology. In the field of drug discovery, we elucidate the structure of target
proteins that cause diseases. Based on the information of its structure, molecules
that exactly fit the protein, i.e., drugs, are designed and synthesized. In the field
of structural biology, studies are being made to elucidate functions from protein
structures. In these fields, in order to determine the structure of a protein, X-ray
crystallography is carried out after crystallizing the protein [1]. In Japan, synchrotron
radiation facilities such as SPring-8 have been built, and the technology of crystal
T. Okutsu (B)
Division of Molecular Science Graduate School of Science and Technology, Gunma University,
1-5-1 Tenjin-cho, Kiryu-shi, Gunma-ken 376-8515, Japan
e-mail: okutsu@gunma-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2020
M. Sakamoto and H. Uekusa (eds.), Advances in Organic Crystal Chemistry,
https://doi.org/10.1007/978-981-15-5085-0_4
71
Crystal Nucleation of Proteins Induced
by Surface Plasmon Resonance
Tetsuo Okutsu
Abstract The crystallization of lysozyme and ribonucleaseA was induced using
photochemical reactions triggered by surface plasmon resonance of gold nanostructures. The tryptophan residues of the protein are radicalized by the enhanced electric field induced by surface plasmon resonance. This radical reacts in the protein
molecule to produce a reaction intermediate in which a nearby tyrosine residue is
radicalized. This reaction intermediate reacts with another protein to form a dimer
linked by tyrosine residues. Since this dimer is covalently bonded, it is stable without
decomposition. With this as a nucleus, it grows into a crystal. An enhanced electric
field induced by surface plasmon resonance of gold nanostructures was used to radicalize amino acids in proteins. Surface plasmon resonance induced by visible light
radicalizes amino acids by the same mechanism as multiphoton absorption. When
a metastable solution of lysozyme and ribonucleaseA was dropped on the substrate
on which the gold nanostructure was constructed, and surface plasmon resonance of
the gold nanostructure was induced, crystals precipitated.
Keywords Surface plasmon resonance · Protein crystallization · Lysozyme ·
RibonucleaseA · Gold nanostructure
4.1 Introduction
Experiments to crystallize proteins are important in the fields of drug discovery and
structural biology. In the field of drug discovery, we elucidate the structure of target
proteins that cause diseases. Based on the information of its structure, molecules
that exactly fit the protein, i.e., drugs, are designed and synthesized. In the field
of structural biology, studies are being made to elucidate functions from protein
structures. In these fields, in order to determine the structure of a protein, X-ray
crystallography is carried out after crystallizing the protein [1]. In Japan, synchrotron
radiation facilities such as SPring-8 have been built, and the technology of crystal
T. Okutsu (B)
Division of Molecular Science Graduate School of Science and Technology, Gunma University,
1-5-1 Tenjin-cho, Kiryu-shi, Gunma-ken 376-8515, Japan
e-mail: okutsu@gunma-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2020
M. Sakamoto and H. Uekusa (eds.), Advances in Organic Crystal Chemistry,
https://doi.org/10.1007/978-981-15-5085-0_4
71