of acidic macromolecules, distributing on the surface of IM, could either directly
touch with crystals, or distribute in crystals. The SM matching the holes of IM could
combine calcium, and provide nucleation sites. On the contrast, when SM in
solutions, they could inhibit crystal formation. SM proteins mainly determine the
crystal forms in organism, may possibly control crystal growth, and also act
importantly in biominerals concern with cell activities, such as ion transportation,
enzyme regulation, and hormone (Qiao et al. 2008a). In studies of Feng et al.
(2000a), Falini et al. (1996), Samata et al. (1999), and Kono et al. (2000), it showed
that in the mineralization process, IM proteins mainly act as structure frames,
providing nucleation sites for calcium carbonate crystals, while SM proteins control
the polymorphs of calcium carbonate crystals.
Many in vitro mineralization experiments have proofed that SM extracted from
calcite biominerals could induce calcite growth, and SM extracted from aragonite
biominerals could induce aragonite growth. For example, the protein matrices
extracted from nacreous layer (aragonite crystals) in mollusk shell Mytilus edulis
induced aragonite formation, while those extracted from prismatic layer (calcite
crystals) induced calcite formation (Feng et al. 2000b). SM extracted by (Belcher
et al. 1996) from shells of Haliotis refescens abalone could well induce aragonite, so
they believed that SM alone could control the polymorph and morphology of calcium
carbonate crystals, IM was not necessary. Feng et al. (2000b) proved that IM from
nacre of shell Mytilus edulis could influence the size and density of the crystals
(Fig. 6.14). While Falini et al. (1996) pointed out that besides SM, IM could also
control calcium carbonate crystal polymorphs. They chose SM from biominerals with
different calcium carbonate crystals, while IM from b-chitin and silk-fibroins of other
animals, adding them into the system with different combinations. The results showed
that SM and IM together could induce the same CaCO 3 crystal form with the
biominerals of which SM were extracted, but b-chitin and SM together without silk
fibroin could only induce calcite crystals, no matter whether the SMs were extracted
from nacreous layer (aragonite crystals)or prismatic layer (calcite crystals). On the
other hand, IM alone did not have any influence on the polymorph. The results show
that SM is one of the most important factors for crystal control, but not the only one.
From the above results, we can see that different results with different conditions could
explain a same natural phenomenon, which means that we are still not holding all the
information of protein matrices-mediated biomineralization.
With the development and fulfillment of theories and technologies, new fields of
protein-mediated biomineralization emerged. New protein matrices extraction
methods were developed by Lopez group of National Museum of Natural Science
in Paris (Pereira-Mourie `s et al. 2002). Acetic acid and Milli-Q water, replacing
EDTA, were used in experiments in order to avoid the potential damage of protein
structures. In this way, water-soluble matrix (WSM), acid-soluble matrix (ASM),
and acid-insoluble matrix (AIM) can be extracted from pearls. Pearls produced by
the freshwater mussel Hyriopsis cumingii crystallize sometimes in the form of
vaterite instead of aragonite. Using this new extraction protocol, the so-called
water-soluble organic matrix, WSM, was extracted and used as additive in controlled calcium carbonate growth experiments. Vaterite crystals were grown for the
6 Principles of Calcium-Based Biomineralization
171
touch with crystals, or distribute in crystals. The SM matching the holes of IM could
combine calcium, and provide nucleation sites. On the contrast, when SM in
solutions, they could inhibit crystal formation. SM proteins mainly determine the
crystal forms in organism, may possibly control crystal growth, and also act
importantly in biominerals concern with cell activities, such as ion transportation,
enzyme regulation, and hormone (Qiao et al. 2008a). In studies of Feng et al.
(2000a), Falini et al. (1996), Samata et al. (1999), and Kono et al. (2000), it showed
that in the mineralization process, IM proteins mainly act as structure frames,
providing nucleation sites for calcium carbonate crystals, while SM proteins control
the polymorphs of calcium carbonate crystals.
Many in vitro mineralization experiments have proofed that SM extracted from
calcite biominerals could induce calcite growth, and SM extracted from aragonite
biominerals could induce aragonite growth. For example, the protein matrices
extracted from nacreous layer (aragonite crystals) in mollusk shell Mytilus edulis
induced aragonite formation, while those extracted from prismatic layer (calcite
crystals) induced calcite formation (Feng et al. 2000b). SM extracted by (Belcher
et al. 1996) from shells of Haliotis refescens abalone could well induce aragonite, so
they believed that SM alone could control the polymorph and morphology of calcium
carbonate crystals, IM was not necessary. Feng et al. (2000b) proved that IM from
nacre of shell Mytilus edulis could influence the size and density of the crystals
(Fig. 6.14). While Falini et al. (1996) pointed out that besides SM, IM could also
control calcium carbonate crystal polymorphs. They chose SM from biominerals with
different calcium carbonate crystals, while IM from b-chitin and silk-fibroins of other
animals, adding them into the system with different combinations. The results showed
that SM and IM together could induce the same CaCO 3 crystal form with the
biominerals of which SM were extracted, but b-chitin and SM together without silk
fibroin could only induce calcite crystals, no matter whether the SMs were extracted
from nacreous layer (aragonite crystals)or prismatic layer (calcite crystals). On the
other hand, IM alone did not have any influence on the polymorph. The results show
that SM is one of the most important factors for crystal control, but not the only one.
From the above results, we can see that different results with different conditions could
explain a same natural phenomenon, which means that we are still not holding all the
information of protein matrices-mediated biomineralization.
With the development and fulfillment of theories and technologies, new fields of
protein-mediated biomineralization emerged. New protein matrices extraction
methods were developed by Lopez group of National Museum of Natural Science
in Paris (Pereira-Mourie `s et al. 2002). Acetic acid and Milli-Q water, replacing
EDTA, were used in experiments in order to avoid the potential damage of protein
structures. In this way, water-soluble matrix (WSM), acid-soluble matrix (ASM),
and acid-insoluble matrix (AIM) can be extracted from pearls. Pearls produced by
the freshwater mussel Hyriopsis cumingii crystallize sometimes in the form of
vaterite instead of aragonite. Using this new extraction protocol, the so-called
water-soluble organic matrix, WSM, was extracted and used as additive in controlled calcium carbonate growth experiments. Vaterite crystals were grown for the
6 Principles of Calcium-Based Biomineralization
171