A thorough investigation of the mode of action of Aspergillus niger (4M-147) pectin lyase A (PLA) on differently C(6)-substituted oligogalacturonides is described. PLA appeared to be very specific for fully methyl-esterified oligogalacturonides: removal of the methyl-ester or changing the type of ester (ethyl esterification) or transamidation resulted in (almost) complete loss of conversion. Th...

Altered chondrocyte differentiation, including development of chondrocyte hypertrophy, mediates osteoarthritis and pathologic articular cartilage matrix calcification. Similar changes in endochondral chondrocyte differentiation are essential for physiologic growth plate mineralization. In both articular and growth plate cartilages, chondrocyte hypertrophy is associated with up-regulated express...

1 At 76 kD with 686 amino acids, tissue transglutaminase (TG2) is a calcium-dependent multifunctional enzyme that catalyzes post-translational modification of specific glutamine residues. TG2 is a ubiquitous enzyme functioning at various cell locations and plays important roles in many cellular processes including cell death, cell movement, adhesion, and proliferation. Even though TG2 possesses...

Tissue transglutaminase (tTG) is a calcium-dependent enzyme that catalyzes the posttranslational modification of proteins by transamidation of specific polypeptide-bound glutamine residues. Previous in vitro studies have demonstrated that the transamidating activity of tTG requires calcium and is inhibited by GTP. To investigate the endogenous regulation of tTG, a quantitative in situ transglut...

The variant surface glycoproteins (VSG) of Trypanosoma brucei are anchored to the cell surface via a glycosylphosphatidylinositol (GPI) anchor. All GPI-anchored proteins are synthesized with a C-terminal signal sequence, which is replaced by a GPI-anchor in a rapid post-translational transamidation reaction. VSG GPI signal sequences are extraordinarily conserved. They contain either 23 or 17 am...

Arterial calcification is a phenotype of vascular repair in atherosclerosis, diabetes, hyperphosphatemic renal failure, and aging. Arterial calcification is modulated by transition of arterial smooth muscle cells (SMCs) from contractile to chondro-osseous differentiation programmed in response to increases in P(i), bone morphogenetic protein-2, and certain other stimuli. Transglutaminase (TG)2 ...

Tissue transglutaminase (TGase) exhibits both a GTP binding/hydrolytic capability and an enzymatic transamidation activity. Increases in TGase expression and activation often occur in response to stimuli that promote cellular differentiation and apoptosis, yet the signaling mechanisms used by these stimuli to regulate TGase expression and activation and the role of TGase in these cellular proce...

In earlier studies"2 on the purification and properties of beef spleen cathepsin C, it was found that at pH 5 this proteolytic enzyme catalyzes the hydrolysis, not only of the CO-NH bonds of sensitive substrates, but also of the ester linkage of a-L-glutamyl-L-tyrosine ethyl ester. In view of the subsequent finding4 that cathepsin C exhibits pronounced specificity toward dipeptide derivatives (...