2
1 Melanin Chemistry
engineering, drug design science, and biomaterials, to artificially reproduce and
improve such functions of organisms. Toward realization of such reaction design,
fundamental understanding of microscopic behaviors of biochemical reactions is
necessary.
Recent development of computational science for physics and chemistry problems
has enabled us to simulate the electronic states of biomolecules based on quantum
theory. Computational materials design (CMD
® ), which guides material functionalization or reaction prediction without fitting to experimental data, is now a generally
accepted framework for creation of intellectual properties. First principles calculation, which only requires the atomic numbers and the atomic configurations, is a
basis of CMD
® realizing the analysis and the prediction of nanoscale effects on the
material structures and compositions. To see the wide effectiveness of first principles
calculation methods and future possibilities, this book reviews CMD
® applications
to biochemical reactions as case studies.
1.1.2 Classification of Melanin
Among the natural pigments formed by living organisms, pigments called melanins
with specific chemical properties and structures have been universally discovered.
Melanin shows various protective functions (or conservatively speaking, energyconverting responses), including ultraviolet (UV) absorption and scavenging of
reactive oxygen species (ROS). Although from the 19th century natural pigments
exhibiting black to dark brown color were vaguely called melanins, the chemical
characteristics of these pigments such as their composition and the structure were
not clear. In the 20th century, research progress on these pigments significantly
advanced the chemical understanding. In the stream of these chemical studies, the
term melanin was defined and classified based on its chemical characteristics and
became almost the same meaning as the one currently used [1].
From a chemical point of view, melanin can be classified into two types. One
is brown to black eumelanin, and another is yellow to reddish brown pheomelanin
[2]. Natural melanins are mixtures of these two types of melanin, and the mixture
ratio forms the various colors of the animal body [3]. Eumelanin is synthesized from
indollic monomers while pheomelanin includes benzothiazine and benzothiazole as
monomers.
In the field of cell biology, melanin-synthesizing cells (pigment cells) have been
studied up-to-date. In the case of homotherm, there are two types of pigment
cell: melanocyte and retinal pigment epithelium (RPE) cell. Pigment cells contain
specialized organelles for melanin production called melanosomes [4].
Melanocytes are neural crest-derived cells, which deliver melanin-containing
melanosomes to the skin and the hair [5]. In the case of poikilotherm, instead of
melanocytes in homotherm, neural crest-derived melanophores exist as melanincontaining cells that control the body colors by varying their distribution.
1 Melanin Chemistry
engineering, drug design science, and biomaterials, to artificially reproduce and
improve such functions of organisms. Toward realization of such reaction design,
fundamental understanding of microscopic behaviors of biochemical reactions is
necessary.
Recent development of computational science for physics and chemistry problems
has enabled us to simulate the electronic states of biomolecules based on quantum
theory. Computational materials design (CMD
® ), which guides material functionalization or reaction prediction without fitting to experimental data, is now a generally
accepted framework for creation of intellectual properties. First principles calculation, which only requires the atomic numbers and the atomic configurations, is a
basis of CMD
® realizing the analysis and the prediction of nanoscale effects on the
material structures and compositions. To see the wide effectiveness of first principles
calculation methods and future possibilities, this book reviews CMD
® applications
to biochemical reactions as case studies.
1.1.2 Classification of Melanin
Among the natural pigments formed by living organisms, pigments called melanins
with specific chemical properties and structures have been universally discovered.
Melanin shows various protective functions (or conservatively speaking, energyconverting responses), including ultraviolet (UV) absorption and scavenging of
reactive oxygen species (ROS). Although from the 19th century natural pigments
exhibiting black to dark brown color were vaguely called melanins, the chemical
characteristics of these pigments such as their composition and the structure were
not clear. In the 20th century, research progress on these pigments significantly
advanced the chemical understanding. In the stream of these chemical studies, the
term melanin was defined and classified based on its chemical characteristics and
became almost the same meaning as the one currently used [1].
From a chemical point of view, melanin can be classified into two types. One
is brown to black eumelanin, and another is yellow to reddish brown pheomelanin
[2]. Natural melanins are mixtures of these two types of melanin, and the mixture
ratio forms the various colors of the animal body [3]. Eumelanin is synthesized from
indollic monomers while pheomelanin includes benzothiazine and benzothiazole as
monomers.
In the field of cell biology, melanin-synthesizing cells (pigment cells) have been
studied up-to-date. In the case of homotherm, there are two types of pigment
cell: melanocyte and retinal pigment epithelium (RPE) cell. Pigment cells contain
specialized organelles for melanin production called melanosomes [4].
Melanocytes are neural crest-derived cells, which deliver melanin-containing
melanosomes to the skin and the hair [5]. In the case of poikilotherm, instead of
melanocytes in homotherm, neural crest-derived melanophores exist as melanincontaining cells that control the body colors by varying their distribution.