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Unique Specificity (unique + specificity)
Selected AbstractsNew ways to break an old bond: the bacterial carbon,phosphorus hydrolases and their role in biogeochemical phosphorus cyclingENVIRONMENTAL MICROBIOLOGY, Issue 10 2007John P. Quinn Summary Phosphonates are organophosphorus molecules that contain the highly stable C,P bond, rather than the more common, and more labile, C,O,P phosphate ester bond. They have ancient origins but their biosynthesis is widespread among more primitive organisms and their importance in the contemporary biosphere is increasingly recognized; for example phosphonate-P is believed to play a particularly significant role in the productivity of the oceans. The microbial degradation of phosphonates was originally thought to occur only under conditions of phosphate limitation, mediated exclusively by the poorly characterized C,P lyase multienzyme system, under Pho regulon control. However, more recent studies have demonstrated the Pho-independent mineralization by environmental bacteria of three of the most widely distributed biogenic phosphonates: 2-aminoethylphosphonic acid (ciliatine), phosphonoacetic acid, and 2-amino-3-phosphonopropionic acid (phosphonoalanine). The three phosphonohydrolases responsible have unique specificities and are members of separate enzyme superfamilies; their expression is regulated by distinct members of the LysR family of bacterial transcriptional regulators, for each of which the phosphonate substrate of the respective degradative operon serves as coinducer. Previously no organophosphorus compound was known to induce the enzymes required for its own degradation. Whole-genome and metagenome sequence analysis indicates that the genes encoding these newly described C,P hydrolases are distributed widely among prokaryotes. As they are able to function under conditions in which C,P lyases are inactive, the three enzymes may play a hitherto-unrecognized role in phosphonate breakdown in the environment and hence make a significant contribution to global biogeochemical P-cycling. [source] Development of a Novel Immunoradiometric Assay Exclusively for Biologically Active Whole Parathyroid Hormone 1,84: Implications for Improvement of Accurate Assessment of Parathyroid FunctionJOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2001Ping Gao Abstract We developed a novel immunoradiometric assay (IRMA; whole parathyroid hormone [PTH] IRMA) for PTH, which specifically measures biologically active whole PTH(1,84). The assay is based on a solid phase coated with anti-PTH(39,84) antibody, a tracer of125I-labeled antibody with a unique specificity to the first N-terminal amino acid of PTH(1,84), and calibrators of diluted synthetic PTH(1,84). In contrast to the Nichols intact PTH IRMA, this new assay does not detect PTH(7,84) fragments and only detects one immunoreactive peak in chromatographically fractionated patient samples. The assay was shown to have an analytical sensitivity of 1.0 pg/ml with a linear measurement range up to 2300 pg/ml. With this assay, we further identified that the previously described non-(1,84)PTH fragments are aminoterminally truncated with similar hydrophobicity as PTH(7,84), and these PTH fragments are present not only in patients with secondary hyperparathyroidism (2° -HPT) of uremia, but also in patients with primary hyperparathyroidism (1° -HPT) and normal persons. The plasma normal range of the whole PTH(1,84) was 7,36 pg/ml (mean ± SD: 22.7 ± 7.2 pg/ml, n = 135), whereas over 93.9% (155/165) of patients with 1° -HPT had whole PTH(1,84) values above the normal cut-off. The percentage of biologically active whole PTH(1,84) (pB%) in the pool of total immunoreactive "intact" PTH is higher in the normal population (median: 67.3%; SD: 15.8%; n = 56) than in uremic patients (median:53.8%; SD: 15.5%; n = 318; p < 0.001), although the whole PTH(1,84) values from uremic patients displayed a more significant heterogeneous distribution when compared with that of 1° -HPT patients and normals. Moreover, the pB% displayed a nearly Gaussian distribution pattern from 20% to over 90% in patients with either 1° -HPT or uremia. The specificity of this newly developed whole PTH(1,84) IRMA is the assurance, for the first time, of being able to measure only the biologically active whole PTH(1,84) without cross-reaction to the high concentrations of the aminoterminally truncated PTH fragments found in both normal subjects and patients. Because of the significant variations of pB% in patients, it is necessary to use the whole PTH assay to determine biologically active PTH levels clinically and, thus, to avoid overestimating the concentration of the true biologically active hormone. This new assay could provide a more meaningful standardization of future PTH measurements with improved accuracy in the clinical assessment of parathyroid function. [source] Immunoglobulin 1 (IgG1) Fc-glycosylation profiling of anti-citrullinated peptide antibodies from human serumPROTEOMICS - CLINICAL APPLICATIONS, Issue 1 2009H. Ulrich Scherer Abstract In several autoimmune disorders, including rheumatoid arthritis (RA), autoantibodies are thought to be the driving force of pathogenicity. Glycosylation of the Fc-part of human Igs is known to modulate biological activity. Hitherto, glycosylation of human IgG-Fc has been analyzed predominantly at the level of total serum IgG, revealing reduced galactosylation in RA. Given the pathogenic relevance of autoantibodies in RA, we wished, in the present study, to address the question whether distinct Fc-glycosylation features are observable at the level of antigen-specific IgG subpopulations. For this purpose, we have developed a method for the microscale purification and Fc-glycosylation analysis of anti-citrullinated peptide antibodies (ACPA). ACPA represent a group of autoantibodies that occur with unique specificity in RA patients. Their presence is associated with increased inflammatory disease activity and rapid joint destruction. Results indicate that ACPA of the IgG1 subclass vary considerably from total serum IgG1 with respect to Fc-galactosylation, with galactosylation being higher on ACPA than on serum IgG1 for some patients, while other patients show higher galactosylation on serum IgG1 than on ACPA. Using this method, studies can be performed on the biological and clinical relevance of ACPA glycosylation within RA patient cohorts. [source] Glycan profiling of anti,citrullinated protein antibodies isolated from human serum and synovial fluidARTHRITIS & RHEUMATISM, Issue 6 2010Hans U. Scherer Objective Anti,citrullinated protein antibodies (ACPA) exhibit unique specificity for rheumatoid arthritis. However, it is incompletely understood whether and how ACPA contribute to disease pathogenesis. The Fc part of human IgG carries 2 N-linked glycan moieties that are crucial for the structural stability of the antibody and that modulate both its binding affinity to Fc, receptors and its ability to activate complement. We undertook this study to analyze Fc glycosylation of IgG1 ACPA in serum and synovial fluid (SF) in order to further characterize the immune response to citrullinated antigens. Methods ACPA were isolated by affinity purification using cyclic citrullinated peptides as antigen. IgG1 Fc glycosylation was analyzed by mass spectrometry. ACPA IgG1 glycan profiles were compared with glycan profiles of total serum IgG1 obtained from 85 well-characterized patients. Glycan profiles of paired SF and serum samples were available from 11 additional patients. Results Compared with the pool of serum IgG1, ACPA IgG1 lacked terminal sialic acid residues. In SF, ACPA were highly agalactosylated and lacked sialic acid residues, a feature that was not detected for total SF IgG1. Moreover, differential ACPA glycan profiles were detected in rheumatoid factor (RF),positive and RF-negative patients. Conclusion ACPA IgG1 exhibit a specific Fc-linked glycan profile that is distinct from that of total serum IgG1. Moreover, Fc glycosylation of ACPA differs markedly between SF and serum. Since Fc glycosylation directly affects the recruitment of Fc-mediated effector mechanisms, these data could further our understanding of the contribution of ACPA to disease pathogenesis. [source] | |||||||||||||