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131.
Physical properties and Tris inhibition of an insect trehalase and a thermodynamic approach to the nature of its active site 总被引:1,自引:0,他引:1
The midgut from Rhynchosciara americana larvae display a trehalase (alpha,alpha'-trehalose glucohydrolase, EC 3.2.1.28) which is soluble with a molecular weight of 122 000 and pI 4.6. The optimum pH of the enzyme is 6.0, its apparent Km for trehalose is 0.67 mM and its energy of activation is 16.7 kcal/mol. Sulfhydryl reagents do not inhibit the trehalase. The results suggest the existence of two carboxyl groups in the active site, one of which has a very high (8.3) pK. The increase of the pK values of the essential groups of the free enzyme in the presence of increasing concentrations of dioxane supports the hypothesis that these groups are carboxyls. The purified enzyme hydrolyzes only alpha,alpha'-trehalose and it is competitively inhibited by several compounds. 相似文献
132.
An indirect antiglobulin immunoperoxidase test was developed for the serological diagnosis of American Trypanosomiasis. Purified rabbit antihuman IgG was labeled with the enzyme and the conjugate so obtained was characterized according to its immune and enzymatic activities, with the help of such parameters as the authors have recently described. For a maximal sensitivity in the tests, high antibody levels and a high-labeling ratio were chosen, as well as dilutions of conjugate ensuring maximal reactivity. Positive tests were found in all 90 serum samples from patients with Chagas' disease and titers did not differ significantly from those observed in immunofluorescence tests done in parallel. The specificity of both tests was also similar, as indicated by the results found for serum samples from 60 patients with other diseases, parasitic or not, showing high levels of antibodies against other infective agents or autoantibodies, and in 15 normals. 相似文献
133.
M Goossens M C Garel J Auvinet O Basset P Ferreira Gomes J Rosa N Arous 《FEBS letters》1975,58(1):149-154
134.
Michel De Wilde Teresa Cabezón Raimundo Villarroel Albert Herzog Alex Bollen 《Molecular & general genetics : MGG》1975,142(1):19-33
Summary Two spontaneous mutants of Escherichia coli strain KMBL-146 selected for resistance to the aminoglycoside antibiotic neamine show severe restriction of amber suppressors in vivo. Purified ribosomes from the mutant strains exhibit low neamine-induced misreading in vitro and a decreased affinity for the related antibiotic streptomycin.Biochemical analysis shows that the mutants each have two modified 30S ribosomal proteins, S12 and S5. In agreement with these results, genetic analysis shows that two mutations are present, neither of which confers resistance to neamine by itself; the mutation located in gene rpxL (the structural gene for protein S12) confers streptomycin dependence but this dependence is suppressed in the presence of the second mutation, located in gene rpxE (the structural gene for protein S5). 相似文献
135.
Jayr de Paiva Campello Sebastião Ferreira Fonseca Ching-Jer Chang Ernest Wenkert 《Phytochemistry》1975,14(1):243-248
Sitosterol and the following terpenic compounds have been isolated from the bark of Podocarpus lambertius: 3β-hydroxytotarol, 4β-carboxynortotarol, and macrophyllic and lambertic acids. The leaves yielded sitosterol, stigmastan-3β,5α-diol-6-one, isopimaric acid, phyllocladene, isophyllocladene, 8,9-abieten-15-ol and 17-isophyllocladenol. 相似文献
136.
John S. D. Bacon Alex H. Gordon E. Jane Morris Victor C. Farmer 《The Biochemical journal》1975,149(2):485-487
O-Acetyl groups were detected by i.r. spectroscopy in cell-wall preparations from grasses and other higher plants and their presence was confirmed chemically. The amounts present are likely to influence both the physical state of the cell-wall polysaccharides and also their digestion by enzymes. 相似文献
137.
138.
139.
Luiz Henrique Soares de Andrade Wilson Max Almeida Monteiro de Moraes Eduardo Hiroshi Matsuo Junior Elizabeth de Orleans Carvalho de Moura Hanna Karen Moreira Antunes Jairo Montemor Ednei Luiz Antonio Danilo Sales Bocalini Andrey Jorge Serra Paulo José Ferreira Tucci Patricia Chakur Brum Alessandra Medeiros 《Molecular and cellular biochemistry》2015,402(1-2):193-202
140.
Alex Paton 《BMJ (Clinical research ed.)》1983,286(6370):1030-1031