Number Of Aspartic Acid Residues Research Articles

Longer Inactivating Sequence in Peptide Lock Improves Performance of Synthetic Protease-Activatable Adeno-Associated Virus.

Adeno-associated viruses (AAVs) are promising gene therapy vectors but may exhibit off-target delivery due to broad tissue tropism. We recently developed a synthetic protease-activatable AAV vector, named provector, that transduces cells preferentially in environments rich in matrix metalloproteinases (MMPs) which are elevated in a variety of diseases, including various cancers and heart diseases. The provector displays peptide locks made up of MMP recognition sites flanking an inactivating sequence (IS) composed of four aspartic acid residues (D4). When present, the IS prevents AAV from binding cell receptors and no transduction occurs (OFF state). High levels of MMPs cleave the recognition sequences and release the IS from the capsid surface, restoring cell receptor binding (ON state). The AAV9 provector prototype is not optimal as it displays baseline OFF transduction at 5-10% of that of the wild-type capsid, which can lead to off-target delivery. We hypothesized that changes to the IS may decrease OFF state transduction. We created a provector panel with IS of lengths 0 (D0) to 10 (D10) aspartic acid residues and characterized this panel in vitro. Notably, we find that the D10 provector has an OFF transduction of less than 1% of wild-type capsid and an ON/OFF transduction ratio of 27, the best outcome achieved for any provector thus far. In summary, our results enable us to define new design rules for the provector platform, specifically that (1) the IS is necessary for provector locking and (2) increasing the number of aspartic acid residues in this sequence improves locking.

Adsorption characteristics of oligopeptides composed of acidic and basic amino acids on titanium surface

The adsorption characteristics of octapeptides, containing different numbers of aspartic acid, lysine, and alanine residues (i.e., D(4)K(0)A(4), D(4)K(1)A(3), D(4)K(3)A(1), D(4)K(4)A(0), and D(0)K(4)A(4)) on the surface of titanium (Ti) particles were investigated in the pH range of 3.0-8.8 at 30 degrees C. The adsorption isotherms for octapeptides having four plural aspartic acid residues with or without lysine residues showed two distinct adsorption modes, i.e., irreversible and reversible modes, at pHs 3.0-6.5; at pH 7.0 or higher, the adsorption mode was reversible. Increasing the number of lysine residues at a fixed number of aspartic acid residues (i.e., 4) decreased the amount of peptides adsorbed in both modes. D(4)K(4)A(0) adsorbed irreversibly at pHs 3.0-6.5, due to the fact that negatively charged carboxyl groups directly interact with a positively charged Ti surface, whereas positively charged amino groups of lysine residues are directed in an opposite direction toward the solution side, as predicted by molecular mechanics/dynamics calculations.

Lack of association of a variable number of aspartic acid residues in the asporin gene with osteoarthritis susceptibility: case-control studies in Spanish Caucasians

A recent genetic association study has identified a microsatellite in the coding sequence of the asporin gene as a susceptibility factor for osteoarthritis (OA). Alleles of this microsatellite determine the variable number of aspartic acid residues in the amino-terminal end of the asporin protein. Asporin binds directly to the growth factor transforming growth factor beta and inhibits its anabolic effects in cartilage, which include stimulation of collagen and aggrecan synthesis. The OA-associated allele, with 14 aspartic acid residues, inhibits the anabolic effects of transforming growth factor beta more strongly than other asporin alleles, leading to increased OA liability. We have explored whether the association found in several cohorts of Japanese hip OA and knee OA patients was also present in Spanish Caucasians. We studied patients that had undergone total joint replacement for primary OA in the hip (n = 303) or the knee (n = 188) and patients with hand OA (n = 233), and we compared their results with controls (n = 294) lacking overt OA clinical symptoms. No significant differences were observed in any of the multiple comparisons performed, which included global tests of allele frequency distributions and specific comparisons as well as stratification by affected joint and by sex. Our results, together with reports from the United Kingdom and Greece, indicate that the stretch of aspartic acid residues in asporin is not an important factor in OA susceptibility among European Caucasians. It remains possible that lifestyle, environmental or genetic differences allow for an important effect of asporin variants in other ethnic groups as has been reported in the Japanese, but this should be supported by additional studies.

CHARACTERIZATION OF LAMPREY FIBRINOPEPTIDES

1. Lamprey fibrinopeptide B is a relatively large peptide made up of about 40 amino acid residues. The peptide is highly electronegative, containing a large number of aspartic acid residues and a tyrosine O-sulphate residue. 2. The amino acid sequence of the first 18 residues from the N-terminal end of fibrinopeptide B has been established. The C-terminal ends with the sequence Val-Arg. Fibrino-peptide B is released by both lamprey and bovine thrombins. 3. Lamprey fibrino-peptide A is a short peptide containing only eight residues. The proposed amino acid sequence is: Asp-Asp-Ser-Ile/Leu-Asp-Ser-Leu/Ile-ArgThis peptide is released by lamprey thrombin but not by bovine thrombin.