pI
3
1 0
Acetic acid-insoluble matrix :
2.6 to 4%
Acetic acid-soluble :
0.25 to 0.30%
PRISMATIC CALCITIC LAYER
PROTEIN NAME
Caspartin
Calprismin
Apparent MW (kDa)
17
37-38
Solubility
Soluble
Soluble
Experimental pI
Around 3 or <
Around 3 or <
Charge property
Polyanionic
Polyanionic
PTMs
No glycosylation
Glycosylation
Dominant AA
B
B, A, T, P
Ca-binding
Weak affinity
Weak affinity
CaCO3 inhibition
Yes - strong
Yes - strong
Interaction with CaCO3
Yes - strong
Yes - Strong
Sequence
Partial
Partial
Affiliation
Asp-rich family (?)
Unknown
Other properties
Self aggregates
Unknown
Localization
Intracrystalline
Co-localizes
& Periprismatic
with caspartin
Present in nacre
10 µm
5 µm
20 µm
20 µm
10 µm
a
b
c
d
e
f
g
h
i
j
k
1
2
3
4
1
2
3
4
5
Fig. 13.5 The calcifying matrix of the shell prismatic layer of Pinna nobilis. (a) Proportions of
soluble and insoluble matrices. (b) Summary of the biochemical properties of caspartin and
calprismin; B is the one-letter symbol for Asx, i.e., Asp or Asn. (c) SDS-PAGE of the
intracrystalline prisms matrix and isolated fractions; lane 1, molecular weight markers, from top
to bottom 94, 67, 43, 30, 20, and 14.4 kDa; lane 2, acetic acid-soluble matrix of isolated prisms;
lane 3, purified caspartin; lane 4, purified calprismin. (d) 2D-gel electrophoresis of the acetic acidsoluble matrix of isolated prisms. (e) Western blot of the acetic acid-soluble matrix of isolated
prisms. The blotted extract was incubated with the polyclonal antibody (dilution 1:3,000) raised
against the purified caspartin; lane 1, molecular weight markers, from top to bottom 116, 97, 66,
45, 31, 21.5, 14.4 and 6.5 kDa; lane 2, acetic acid-soluble matrix of isolated prisms, silver stained;
lanes 3–5, western blot of the acetic acid-soluble matrix of isolated prisms, 5 mg (lane 3), 10 mg
13 Acidic Shell Proteins of the Mediterranean Fan Mussel Pinna nobilis
373
3
1 0
Acetic acid-insoluble matrix :
2.6 to 4%
Acetic acid-soluble :
0.25 to 0.30%
PRISMATIC CALCITIC LAYER
PROTEIN NAME
Caspartin
Calprismin
Apparent MW (kDa)
17
37-38
Solubility
Soluble
Soluble
Experimental pI
Around 3 or <
Around 3 or <
Charge property
Polyanionic
Polyanionic
PTMs
No glycosylation
Glycosylation
Dominant AA
B
B, A, T, P
Ca-binding
Weak affinity
Weak affinity
CaCO3 inhibition
Yes - strong
Yes - strong
Interaction with CaCO3
Yes - strong
Yes - Strong
Sequence
Partial
Partial
Affiliation
Asp-rich family (?)
Unknown
Other properties
Self aggregates
Unknown
Localization
Intracrystalline
Co-localizes
& Periprismatic
with caspartin
Present in nacre
10 µm
5 µm
20 µm
20 µm
10 µm
a
b
c
d
e
f
g
h
i
j
k
1
2
3
4
1
2
3
4
5
Fig. 13.5 The calcifying matrix of the shell prismatic layer of Pinna nobilis. (a) Proportions of
soluble and insoluble matrices. (b) Summary of the biochemical properties of caspartin and
calprismin; B is the one-letter symbol for Asx, i.e., Asp or Asn. (c) SDS-PAGE of the
intracrystalline prisms matrix and isolated fractions; lane 1, molecular weight markers, from top
to bottom 94, 67, 43, 30, 20, and 14.4 kDa; lane 2, acetic acid-soluble matrix of isolated prisms;
lane 3, purified caspartin; lane 4, purified calprismin. (d) 2D-gel electrophoresis of the acetic acidsoluble matrix of isolated prisms. (e) Western blot of the acetic acid-soluble matrix of isolated
prisms. The blotted extract was incubated with the polyclonal antibody (dilution 1:3,000) raised
against the purified caspartin; lane 1, molecular weight markers, from top to bottom 116, 97, 66,
45, 31, 21.5, 14.4 and 6.5 kDa; lane 2, acetic acid-soluble matrix of isolated prisms, silver stained;
lanes 3–5, western blot of the acetic acid-soluble matrix of isolated prisms, 5 mg (lane 3), 10 mg
13 Acidic Shell Proteins of the Mediterranean Fan Mussel Pinna nobilis
373