Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chitotriosidase is a chitinase that is massively expressed by lipid-laden tissue macrophages in man. Its enzymatic activity is markedly elevated in serum of patients suffering from lysosomal lipid storage disorders, sarcoidosis, thalassemia, and visceral Leishmaniasis. Monitoring of serum chitotriosidase activity in Gaucher disease patients during progression and therapeutic correction of their disease is useful to obtain insight in changes in body burden on pathological macrophages. However, accurate quantification of chitotriosidase levels by enzyme assay is complicated by apparent substrate inhibition, which prohibits the use of saturating substrate concentrations. We have therefore studied the catalytic features of chitotriosidase in more detail. It is demonstrated that the inhibition of enzyme activity at excess substrate concentration can be fully explained by transglycosylation of substrate molecules. The potential physiological consequences of the ability of chitotriosidase to hydrolyze as well as transglycosylate are discussed. The novel insight in transglycosidase activity of chitotriosidase has led to the design of a new substrate molecule, 4-methylumbelliferyl-(4-deoxy)chitobiose. With this substrate, which is no acceptor for transglycosylation, chitotriosidase shows normal Michaelis-Menten kinetics, resulting in major improvements in sensitivity and reproducibility of enzymatic activity measurements. The novel convenient chitotriosidase enzyme assay should facilitate the accurate monitoring of Gaucher disease patients receiving costly enzyme replacement therapy.
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PMID:Transglycosidase activity of chitotriosidase: improved enzymatic assay for the human macrophage chitinase. 1289 Jun 86

Chitotriosidase (Chit), a member of the mammalian chitinase family, structurally homologous to chitinases from other species, is synthesized and secreted by specifically activated macrophages. After discovery of a striking increase of plasma Chit activity in serum from Gaucher's disease type I patients, an increasing number of inherited and acquired conditions sharing macrophage activation have been associated with increased Chit activity. In addition to lipid storage disorders, where Chit activity has longer been used as a marker of disease activity and therapeutic response, elevation of plasma Chit may occur in hematological disorders with storage of erythrocyte membrane breakdown products as thalassemia and different systemic infectious diseases sustained by fungi and other pathogens. Recently, increased Chit activity was demonstrated in CNS from patients with different neurological disorders. After a wide range of unwanted stimuli such as those occurring in stroke, multiple sclerosis, and Alzheimer's disease, resident cells like microglia and a few other cell types promptly activate a complex immune cascade which then might be monitored also by measuring Chit activity. The increased activity of Chit, wherever it is documented, represents one ancestral response of innate immunity which may have a wide range of clinical applications.
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PMID:Plasma chitotriosidase in health and pathology. 1760 8