Search results for "Zymogen"
showing 10 items of 14 documents
Characterization of human reflex tear proteome reveals high expression of lacrimal proline-rich protein 4 (PRR4).
2014
In-depth studies on the proteome of reflex tears are still inadequate. Hence, further studies on this subject will unravel the key proteins which are conjectured to possess vital functions in the protection of the ocular surface. Therefore, this study investigated the differences in the expression levels in proteome of reflex compared to basal tears. Basal (n = 10) and reflex (n = 10) tear samples from healthy subjects were collected employing the capillary method, subsequently pooled and the proteomes were characterized employing 1DE combined with LC-ESI-MS/MS strategy for label-free quantitative (LFQ) analysis. The differentially expressed proteins were validated by 2DE combined with LC-E…
Development of a Peptide-Based Sandwich Elisa for Human Tissue Prokallikrein with No Cross-Reactivity from Mature Kallikrein
2000
Human tissue prokallikrein is the enzymatically inactive zymogen of a serine proteinase involved in the liberation of vasoactive kinin peptides, and it is supposed that an impaired prokallikrein-to-kallikrein conversion is closely related to certain hypertensive and inflammatory disorders. Progress in understanding the biological role of the proenzyme has been limited by the absence of an accurate assay for the kallikrein precursor. We describe a sandwich enzyme-linked immunosorbent assay to measure human tissue prokallikrein using monospecific anti-peptide antibodies raised against propeptide derivatives. This method could detect a minimum concentration of 60 pg/ml prokallikrein and displa…
Tumor necrosis factor-alpha converting enzyme is processed by proprotein-convertases to its mature form which is degraded upon phorbol ester stimulat…
2003
Tumor necrosis factor-alpha converting enzyme (TACE or ADAM17) is a member of the ADAM (a disintegrin and metalloproteinase) family of type I membrane proteins and mediates the ectodomain shedding of various membrane-anchored signaling and adhesion proteins. TACE is synthesized as an inactive zymogen, which is subsequently proteolytically processed to the catalytically active form. We have identified the proprotein-convertases PC7 and furin to be involved in maturation of TACE. This maturation is negatively influenced by the phorbol ester phorbol-12-myristate-13-acetate (PMA), which decreases the cellular amount of the mature form of TACE in PMA-treated HEK293 and SH-SY5Y cells. Furthermore…
Effects of sublethal levels of tributyltin chloride on a new toxicity test organism,Liza saliens (osteichthyes, mugilidae): a histological study
2006
The histopathological effects of 10−7 and 10−9M tributyltin(IV)chloride,TBTCl, solutions on different Liza saliens organs have been studied by light microscope. The fish were sacrificed after 3–4 h incubation in 10−7M TBTCl solution or after 15 days incubation in 10−9M solution. The observed histopathological changes were dose- and time-dependent. The 10−7M TBTCl concentration resulted in major damage to the gill epithelium, indicating that TBTCl primarily interfered with the respiration, osmoregulation, acid balance and nitrogenous waste excretion processes. After incubation in 10−9M TBTCl solution the fish lived 20 or more days, but many of the organs were altered. Thymus atrophy, reduced…
Mapping of the high molecular weight kininogen binding site of prekallikrein. Evidence for a discontinuous epitope formed by distinct segments of the…
1993
Prekallikrein, a glycoprotein involved in contact phase activation, circulates in plasma in the form of a binary complex with high molecular weight kininogen (H-kininogen). The binding to H-kininogen is mediated by the prekallikrein heavy chain consisting of four repetitive domains, A1-A4. To define more precisely the region(s) involved in kininogen binding, we have employed an affinity cross-linking strategy with a synthetic peptide of 31 residues which mimics the prekallikrein binding site of H-kininogen. Cross-linking of the radiolabeled peptide to (pre)kallikrein revealed a binding segment in the NH2-terminal portion of the prekallikrein heavy chain; another binding segment was located …
Mapping of the Discontinuous H-kininogen Binding Site of Plasma Prekallikrein
1999
Plasma prekallikrein, a zymogen of the contact phase system, circulates in plasma as heterodimeric complex with H-kininogen. The binding is mediated by the prekallikrein heavy chain consisting of four apple domains, A1 to A4, to which H-kininogen binds with high specificity and affinity (K(D) = 1.2 x 10(-8) M). Previous work had demonstrated that a discontinuous kininogen-binding site is formed by a proximal part located in A1, a distal part exposed by A4, and other yet unidentified portion(s) of the kallikrein heavy chain. To detect relevant binding segment(s) we recombinantly expressed single apple domains and found a rank order of binding affinity for kininogen of A2 > A4 approximately A…
Cellular visualization of tissue prokallikrein in human neutrophils and myelocytes
1999
The vasoactive peptides bradykinin and kallidin (lysyl-bradykinin) have been implicated in diapedesis, a cellular process by which neutrophils migrate through endothelial cell gap junctions. The kinin peptides are released from their precursor moiety, kininogen, by the specific action of endoproteinases, the kallikreins. Kininogens have been demonstrated on the surface of neutrophils, and the presence of a competent processing enzyme such as tissue prokallikrein in neutrophils has been postulated, but firm evidence for this is still lacking. We have raised antibodies to a synthetic peptide that is a sequence copy of the activation segment of human TK and demonstrated that the anti-peptide a…
Enhanced Activity of Meprin-α, a Pro-Migratory and Pro-Angiogenic Protease, in Colorectal Cancer
2011
Meprin-α is a metalloprotease overexpressed in cancer cells, leading to the accumulation of this protease in a subset of colorectal tumors. The impact of increased meprin-α levels on tumor progression is not known. We investigated the effect of this protease on cell migration and angiogenesis in vitro and studied the expression of meprin-α mRNA, protein and proteolytic activity in primary tumors at progressive stages and in liver metastases of patients with colorectal cancer, as well as inhibitory activity towards meprin-α in sera of cancer patient as compared to healthy controls. We found that the hepatocyte growth factor (HGF)- induced migratory response of meprin-transfected epithelial c…
Functional and structural insights into astacin metallopeptidases
2012
The astacins are a family of multi-domain metallopeptidases with manifold functions in metabolism. They are either secreted or membrane-anchored and are regulated by being synthesized as inactive zymogens and also by colocalizing protein inhibitors. The distinct family members consist of N-terminal signal peptides and pro-segments, zincdependent catalytic domains, further downstream extracellular domains, transmembrane anchors, and cytosolic domains. The catalytic domains of four astacins and the zymogen of one of these have been structurally characterized and shown to comprise compact ~200-residue zinc-dependent moieties divided into an N-terminal and a C-terminal sub-domain by an active-s…
Structural basis for the sheddase function of human meprin β metalloproteinase at the plasma membrane.
2012
Ectodomain shedding at the cell surface is a major mechanism to regulate the extracellular and circulatory concentration or the activities of signaling proteins at the plasma membrane. Human meprin β is a 145-kDa disulfide-linked homodimeric multidomain type-I membrane metallopeptidase that sheds membrane-bound cytokines and growth factors, thereby contributing to inflammatory diseases, angiogenesis, and tumor progression. In addition, it cleaves amyloid precursor protein (APP) at the β-secretase site, giving rise to amyloidogenic peptides. We have solved the X-ray crystal structure of a major fragment of the meprin β ectoprotein, the first of a multidomain oligomeric transmembrane sheddase…