Inhibition of apatite crystal growth by the amino-terminal segment of human salivary acidic proline-rich proteins

1984 ◽  
Vol 36 (1) ◽  
pp. 651-658 ◽  
Author(s):  
T. Aoba ◽  
E. C. Moreno ◽  
D. I. Hay
Keyword(s):  
Crystal Growth ◽  
Terminal Segment ◽  
Apatite Crystal ◽  
Amino Terminal

Control of apatite crystal growth in a fluoride containing amelogenin-rich matrix

Biomaterials ◽  
2005 ◽  
Vol 26 (13) ◽  
pp. 1595-1603 ◽  
Author(s):  
M. Iijima ◽  
J. Moradian-Oldak
Keyword(s):  
Crystal Growth ◽  
Apatite Crystal

Structural properties of substrate proteins determine their proteolysis by the mitochondrial AAA+ protease Pim1

2005 ◽  
Vol 386 (12) ◽  
pp. 1307-1317 ◽  
Author(s):  
Birgit von Janowsky ◽  
Karin Knapp ◽  
Tamara Major ◽  
Martin Krayl ◽  
Bernard Guiard ◽  
...  
Keyword(s):  
Structural Properties ◽  
Major Effect ◽  
Terminal Segment ◽  
Mitochondrial Matrix ◽  
Amino Terminal ◽  
In Organello ◽  
Fragment Formation ◽  
Folded Proteins ◽  
Substrate Proteins ◽  
Folding State

Abstract The protease Pim1/LON, a member of the AAA+ family of homo-oligomeric ATP-dependent proteases, is responsible for the degradation of soluble proteins in the mitochondrial matrix. To establish the molecular parameters required for the specific recognition and proteolysis of substrate proteins by Pim1, we analyzed the in organello degradation of imported reporter proteins containing different structural properties. The amino acid composition at the amino-terminal end had no major effect on the proteolysis reaction. However, proteins with an amino-terminal extension of less than 60 amino acids in front of a stably folded reporter domain were completely resistant to proteolysis by Pim1. Substrate proteins with a longer amino-terminal extension showed incomplete proteolysis, resulting in the generation of a defined degradation fragment. We conclude that Pim1-mediated protein degradation is processive and is initiated from an unstructured amino-terminal segment. Resistance to degradation and fragment formation was abolished if the folding state of the reporter domain was destabilized, indicating that Pim1 is not able to unravel folded proteins for proteolysis. We propose that the requirement for an exposed, large, non-native protein segment, in combination with a limited unfolding capability, accounts for the selectivity of the protease Pim1 for damaged or misfolded polypeptides.

Prosomatostatin is proteolytically processed at the amino terminal segment by subtilase SKI-1

2004 ◽  
Vol 120 (1-3) ◽  
pp. 133-140 ◽  
Author(s):  
R Mouchantaf ◽  
H.L Watt ◽  
T Sulea ◽  
N.G Seidah ◽  
H Alturaihi ◽  
...  
Keyword(s):  
Terminal Segment ◽  
Amino Terminal

Possible Roles of Partial Sequences at N- and C-termini of Amelogenin in Protein-Enamel Mineral Interaction

1989 ◽  
Vol 68 (9) ◽  
pp. 1331-1336 ◽  
Author(s):  
T. Aoba ◽  
E.C. Moreno ◽  
M. Kresak ◽  
T. Tanabe
Keyword(s):  
Crystal Growth ◽  
Adsorption Isotherm ◽  
Inhibitory Activity ◽  
Solid Phase ◽  
Ionic Composition ◽  
Significant Inhibition ◽  
Apatite Crystal ◽  
Supersaturated Solution ◽  
Adsorption Sites ◽  
Adsorption Affinity

The purpose of this study was to assess the functional significance of homologous sequences of mammalian amelogenins at their N- and C-termini. A porcine 5-kDa fragment corresponding to the N-terminal 45 residues of amelogenins was purified from the secretory enamel. The decapeptide TDKTKREEVD corresponding to the C-terminal 10 residues of amelogenins was synthesized according to conventional solid-phase procedures. The inhibitory activity of both moieties on apatite crystal growth was determined in a supersaturated solution having an ionic composition similar to that of the fluid phase separated from porcine secretory enamel. The 5-kDa amelogenin fragment was sparingly soluble in neutral solutions and (in condensed forms because of aggregation) showed no significant inhibition of crystal growth, whereas the fragment molecules pre-adsorbed onto the seed crystals yielded modest inhibition of hydroxyapatite precipitation. However, their inhibitory activity was significantly lower than that of parent porcine amelogenin (25-kDa molecular mass). The high solubility of synthesized decapeptide allowed us to determine the adsorption isotherm onto hydroxyapatite at 37°C, at an ionic strength similar to that of the enamel fluid. The obtained adsorption isotherm was described by a Langmuir model; the adsorption affinity and the maximum adsorption sites were 6.2 mL/μmol and 0.53 μmol/m2, respectively. As expected from the low adsorption affinity, the peptide showed a much weaker inhibition of apatite crystal growth than the parent amelogenin. All the foregoing results suggest that the adsorption onto apatite crystals and any inhibition of crystal growth by the amelogenin macromolecules cannot be associated with either partial molecular sequence, but may be determined by the whole molecular structure, including both segments at the N- and C-termini.

Structure of an insulin dimer in an orthorhombic crystal: the structure analysis of a human insulin mutant (B9 Ser→Glu)

1999 ◽  
Vol 55 (9) ◽  
pp. 1524-1532 ◽  
Author(s):  
Zhi-Ping Yao ◽  
Zong-Hao Zeng ◽  
Hong-Min Li ◽  
Ying Zhang ◽  
You-Min Feng ◽  
...  
Keyword(s):  
Human Insulin ◽  
Solution Structure ◽  
Building Blocks ◽  
Structural Rearrangement ◽  
Crystal Form ◽  
Terminal Segment ◽  
Orthorhombic Crystal ◽  
Amino Terminal ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The structure of human insulin mutant B9 (Ser→Glu) was determined by an X-ray crystallographic method at 2.5 Å resolution with an R factor of 0.165 under non-crystallographic restraints. The crystals were grown at low pH (<3.8) and belong to the orthorhombic P212121 space group with unit-cell dimensions a = 44.54, b = 46.40, c = 51.85 Å and one dimer per asymmetric unit without further aggregation. The structure in this crystal form can be regarded as a model for a discrete insulin dimer and displays the following features compared with the structure of 2Zn insulin. (i) The overall dimer is expanded and more symmetric. The two A chains are about 2 Å more distant from each other, while the two B chains are about 0.8 Å further apart. Both monomers are more similar to molecule 1 than molecule 2 of the 2Zn insulin dimer. (ii) The dimer structure is stabilized by protonation and neutralization of the carboxyl groups at lower pH and, in addition, by formation of a hydrogen-bond network among the side chains of residues GluB9, HisB13 and HisB10 on the dimer-forming surface of both monomers, resulting from a structural rearrangement. (iii) The B-chain amino-terminal segment is in an open state (O state), i.e. a state different from the well known R and T states found in the insulin hexamer. In the O state, the B-chain N-terminal segment is in an extended conformation and is detached from the rest of the molecule. This conformational state has also been observed in the monomeric crystal structure of despentapeptide (B26–B30) and desheptapeptide (B24–B30) insulin, as well as in the solution structure of an engineered insulin monomer. It suggests that the O state may be the characteristic conformation of insulin in lower aggregation forms and may be relevant to the formation of insulin fibrils. In addition, based on the crystallization process, the smallest possible building blocks of insulin crystal are also discussed.

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