RESUMO
(1) The serine protease inhibitor Kazal type 1 (SPINK1) inhibits trypsin activity in zymogen granules of pancreatic acinar cells. Several mutations in the SPINK1 gene are associated with acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP). The most common variant is SPINK1 p.N34S. Although this mutation was identified two decades ago, the mechanism of action has remained elusive. (2) SPINK1 and human cationic trypsin (TRY1) were expressed in E. coli, and inhibitory activities were determined. Crystals of SPINK1-TRY1 complexes were grown by using the hanging-drop method, and phases were solved by molecular replacement. (3) Both SPINK1 variants show similar inhibitory behavior toward TRY1. The crystal structures are almost identical, with minor differences in the mutated loop. Both complexes show an unexpected rotamer conformation of the His63 residue in TRY1, which is a member of the catalytic triad. (4) The SPINK1 p.N34S mutation does not affect the inhibitory behavior or the overall structure of the protein. Therefore, the pathophysiological mechanism of action of the p.N34S variant cannot be explained mechanistically or structurally at the protein level. The observed histidine conformation is part of a mechanism for SPINK1 that can explain the exceptional proteolytic stability of this inhibitor.
Assuntos
Pancreatite Crônica , Inibidor da Tripsina Pancreática de Kazal , Escherichia coli , Predisposição Genética para Doença , Humanos , Mutação , Pancreatite Crônica/genética , Tripsina/genética , Inibidor da Tripsina Pancreática de Kazal/genéticaRESUMO
Inflammatory diseases of the pancreas can range from acute to acute recurrent and chronic pancreatitis. With the improvement of laboratory diagnostics in the 21st century, the mechanisms of the pro-inflammatory and anti-inflammatory role of tight junctions, in particular the transmembrane proteins occludin, claudine and JAMs, cytoplasmic Zo-proteins, and adherens junctions, in particular -catenin, -catenin, E-cadherin, selectins and ICAMs in the pathogenesis of acute and chronic pancreatitis have become more clear. The study of genetic factors in the development of acute and chronic pancreatitis showed the role of mutations in the genes SPINK1 N34S, PRSS1, CEL-HYB in the progression of the disease.
Assuntos
Pancreatite , Proteínas de Transporte/genética , Predisposição Genética para Doença , Humanos , Mutação , Pâncreas , Pancreatite/diagnóstico , Pancreatite/genética , Tripsina/genética , Inibidor da Tripsina Pancreática de KazalRESUMO
Isotopic studies of nitrogen and sulphur inputs to plant/soil systems commonly rely on limited published data for the 15N/14N and 34S/32S ratios of nitrate, ammonium and sulphate in rainfall. For systems with well-developed plant canopies, however, inputs of these ions from dry deposition or particulates may be more important than rainfall. The manner in which isotopic fractionation between ions and gases may lead to dry deposition and particulates having 15N/14N or 34S/32S ratios different from those of rainfall is considered. Data for rainfall and throughfall in coniferous plantations are then discussed, and suggest that: (1) in line with expectations, nitrate washed from the canopy has 15N/14N ratios higher than those in rainfall; (2) the 15N/14N ratios of ammonium washed from the canopy are variable, with high ratios being found for canopies of higher pH in conditions of elevated ambient ammonia gas concentrations; and (3) in accord with expectations and previous work, 34S/32S ratios of sulphate washed from the canopy are not substantially different from those in rainfall. The study suggests that if atmospheric inputs are relevant to isotopic studies of the sources of nitrogen for canopied systems, then confident interpretation will require analysis of these inputs.