Abstract：
:The interaction of urea with lysozyme was studied in the 192-240 nm spectral region by spectrophotometry. The far and middle ultraviolet protein bands records undergo a non-linear "red shift" and "hypochromic effect" under urea titration. These spectral shifts are interpreted basically in terms of decreasing in molar absorptivity due to the binding of the denaturant with the protein chromophores. Two interaction mechanisms with different chromophores involvement are characterized. One of them is noncooperative and its is evidenced by the analysis either of the red shift or of the hypochromic effect showed by the protein far ultraviolet records in urea up to 2 M. This noncooperative effect is represented by two different and independent classes of binding sites in which the tryptophan side chain and the amide peptide bond unit are involved. The calculated stoichiometric constants give the values of 4.61 M-1 for K1 and of 0.078 M-1 for K2, while the site binding constants have the values of 0.852 M-1 for K1 and 0.086 M-1 for K2. The other mechanism which is detected by the middle U.V. band analysis of the protein in urea concentration up to 8 M shows high cooperativity (Hill coefficient of 2.56). Also in this case, tryptophan residues are involved in the binding process. No significant light-scattering influence on absorption measurements is found.
journal_name
An Acad Bras Ciencjournal_title
Anais da Academia Brasileira de Cienciasauthors
Hampe OG,Hampe MM,Zinner Ksubject
Has Abstractpub_date
1981-03-01 00:00:00pages
33-41issue
1eissn
0001-3765issn
1678-2690journal_volume
53pub_type
杂志文章abstract：:A soil isolate, Penicillium janthinellum sw09 has been found to produce significant amounts of an extracellular pectinase subsequently characterized as exo-polygalacturonase (exo-PG). By optimizing growth conditions, P. janthinellum sw09 produced high amount of exo-PG (16.54 units/mL). The crude enzyme was purified by...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201620150051
更新日期：2016-01-01 00:00:00
abstract：:Cyperaceae is an angiosperm family with the greatest diversity of species with Kranz anatomy. Four different types of Kranz anatomy (chlorocyperoid, eleocharoid, fimbristyloid and rhynchosporoid) have been described for this angiosperm family, and the occurrence and structural characteristics of these types are import...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201520150175
更新日期：2015-10-01 00:00:00
abstract：:Penguins identify their mate or chick by an acoustic signal, the display call. This identification is realized in a particularly constraining environment: the noisy world of a colony of thousands of birds. To fully understand how birds solve this problem of communication, we have done observations, acoustic analysis, ...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/s0001-37652004000200015
更新日期：2004-06-01 00:00:00
abstract：OBJECTIVE:the aim of this study is to map thermal stress risks for human health at the São Francisco River Basin (SFRB) in the Semiarid region, for climatic scenarios RCP 4.5 and 8.5. METHODS:The heat stress conditions were defined by the Wet Bulb Globe Temperature (WBGT) indicator and by the average number of annual ...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201920180748
更新日期：2019-10-07 00:00:00
abstract：:Tissue engineering holds as a prominent technique to repair or replace the damaged human parts to recreate its native function. In this research, a novel scaffold based on polyurethane (PU) comprising megni oil was electrospun for tissue engineering applications. The obtained polyurethane blended with megni oil nanofi...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201920190018
更新日期：2019-06-19 00:00:00
abstract：:Multidrug resistance to chemotherapy is a major obstacle in the treatment of cancer patients. The best characterised mechanism responsible for multidrug resistance involves the expression of the MDR-1 gene product, P-glycoprotein. However, the resistance process is multifactorial. Studies of multidrug resistance mecha...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章,评审
doi：10.1590/s0001-37652001000100007
更新日期：2001-03-01 00:00:00
abstract：:The phosphatidylinositol 3-kinase and mitogen-activated protein kinase pathways mediate β cell growth, proliferation, survival and death. We investigated whether protein restriction during pregnancy alters islet morphometry or the expression and phosphorylation of several proteins involved in the phosphatidylinositol ...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201520140251
更新日期：2015-04-01 00:00:00
abstract：:We investigated reproductive features of the dipsadid snake Erythrolamprus poecilogyrus sublineatus in the southernmost Brazilian coast, a subtropical region characterized by well-marked seasons. Females are significantly smaller than males, have a shorter tail, and reach sexual maturity at later times along their dev...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201720160805
更新日期：2017-01-01 00:00:00
abstract：:The non-dinosaurian dinosauriform silesaurids are the closest relatives of crown-group dinosaurs and are thus, important for understanding the origins of that group. Here, we describe the limb bone histology of the Late Triassic silesaurid Sacisaurus agudoensis from the Candelária Sequence of the Santa Maria Supersequ...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201920180643
更新日期：2019-06-19 00:00:00
abstract：:Two experiments (E) were carried out to evaluate the effects of fumaric acid and an acidifier blend [composed by calcium formate, calcium lactate and medium-chain fatty acids (capric and caprylic)] in piglet diets containing colistin (40 ppm) or halquinol (120 ppm) on performance, diarrhea incidence (E1), organs relat...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201820160057
更新日期：2018-02-19 00:00:00
abstract：:A performance assessment of active magnetocaloric regenerators using entropy generation minimization is presented. The model consists of the Brinkman-Forchheimer equation to describe the fluid flow and coupled energy equations for the fluid and solid phases. Entropy generation contributions due to axial heat conductio...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201720160427
更新日期：2017-05-01 00:00:00
abstract：:Spatial variation in the environment may be an important source of morphological variation in many organisms. Tadpoles are valuable model organisms for studies of morphological variation, and in particular, the evaluation of the relationship between environmental and morphological variables. In heterogeneous environme...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765202020181171
更新日期：2020-11-02 00:00:00
abstract：:One of the most important steps is to clarify the juice, which are added synthetic polymer acrylamide base, aiming the fast settling of impurities present in the juice. However, this input is expensive and may have carcinogenic and neurotoxic actions to humans. The search for new natural flocculants that have similari...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201720170473
更新日期：2017-10-01 00:00:00
abstract：:A total of 40 specimens of the teleost fish Gobioides grahamae Palmer & Wheeler, 1955 were obtained from the municipality of Salvaterra on Marajó Island in the Brazilian state of Pará. Their livers were removed and processed for light microscopy. Overall, 90% of the specimens presented some degree of steatosis of the ...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201420130147
更新日期：2014-09-01 00:00:00
abstract：:Properties of L(+) lactate dehydrogenase (LDH) of Electrophorus electricus (L.) electric organ were studied, comparing the substrates pyruvate and lactate. Electric organ LDH is a soluble enzyme with a pH optimum of 7.4 for pyruvate and 9.0 for lactate. The apparent Km was lower for pyruvate (Km = 2.5 X 10(-4) M) than...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：
更新日期：1976-01-01 00:00:00
abstract：:This paper discusses the facies distribution of Mesozoic eolian sandstones between the Sanga do Cabral and Botucatu formations and also their contact relationships, in São Leopoldo area, State of Rio Grande do Sul (RS), southern Brazil. The main distinctive characteristics regarding these sandstones and formations are...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/s0001-37652000000200010
更新日期：2000-06-01 00:00:00
abstract：:Lyroglossa and Pteroglossa (Orchidaceae: Spiranthinae) are first recorded for Rio Grande do Sul. Descriptions, illustrations, taxonomic notes and distribution are presented. We also provide an artificial key to distinguish the genera of the "Stenorrhynchos Clade" reported so far in Rio Grande do Sul. ...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：
更新日期：2014-06-01 00:00:00
abstract：:The aim of this study was to investigate the polliniferous floral sources used by Apis mellifera (L.) (africanized) in an apiary situated in Pará de Minas, Minas Gerais state, and evaluate the pollen prefences among the beehives. Two beehives of Langstroth type with frontal pollen trap collectors were used. The harves...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/s0001-37652010000200005
更新日期：2010-06-01 00:00:00
abstract：:During composting processes, the degradation of organic waste is accomplished and driven by a succession of microbial populations exhibiting a broad range of functional competencies. A total of 183 bacteria, isolated from a composting process, were evaluated for cellulase activity at different temperatures (37, 50, 60...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201720170408
更新日期：2017-01-01 00:00:00
abstract：:The present work gives continuity in the analysis of the wear influence on cylindrical hydrodynamic bearings by presenting an experimental validation of the wear model previously proposed by the authors. This validation is carried on using the frequency response of the rotor-bearings system in directional coordinates....
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201620150414
更新日期：2016-10-01 00:00:00
abstract：:Twenty-two nitrogen-fixing Bacillus azotofixans strains were shown to produce an inhibition zone against themselves in plate assays. The B. azotofixans type strain P3L-5, chosen for further studies, produced inhibition zones against various Bacillus strains and other bacterial genera. This antibacterial substance was ...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：
更新日期：1990-03-01 00:00:00
abstract：:The intercropping is an important cultural practice commonly used in pest management. It is based on the principle that increased plant diversity in the agro-ecosystem can lead to reductions of pest populations in the crop. The current study aimed to assess the impact the colored fiber cotton-cowpea intercropped syste...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201820160212
更新日期：2018-01-01 00:00:00
abstract：:The use of sensors and optical fibers for monitoring structures is continuously growing. Strains, displacements, accelerations, temperatures are just a few of the monitoring possibilities. In the case of dam structures, concrete face rockfill dams constitute a type of structures where the monitoring of water infiltrat...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201820170144
更新日期：2018-04-01 00:00:00
abstract：:This paper presents a sedimentological and stratigraphical study of Quaternary (Middle to Late Pleistocene/Holocene) continental carbonates outcrops inside Pantanal Basin and its surroundings, especially in Serra da Bodoquena, Pantanal do Miranda and Corumbá/Ladário plateau, in the state of Mato Grosso do Sul, as well...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201720160584
更新日期：2017-05-01 00:00:00
abstract：:The objective of this study was to evaluate the effect of controlled atmosphere (CA) on quality preservation of 'Laetitia' plums, mainly on internal breakdown, in order to determine the best CA storage conditions. Two experiments were carried out one in 2010, and another in 2011. In 2010, besides cold storage (CS; 21....
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765201420130237
更新日期：2014-03-01 00:00:00
abstract：:Establishment of infection by Trypanosoma cruzi, the agent of Chagas' disease, depends on a series of events involving interactions of diverse parasite molecules with host components. Here we focus on the mechanisms of target cell invasion by metacyclic trypomastigotes (MT) and mammalian tissue culture trypomastigotes...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章,评审
doi：10.1590/s0001-37652006000100010
更新日期：2006-03-01 00:00:00
abstract：:We investigated the morphologic and functional changes of infarcted rat hearts under a paradigm of angiotensinconverting enzyme inhibition. Myocardial infarction was induced by left coronary artery ligation and a control group (SHAM) underwent sham-operation. Infarcted rats received normal drinking water with (CAP gro...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/s0001-37652007000200008
更新日期：2007-06-01 00:00:00
abstract：:A relevant series of symmetric supramolecular porphyrins has been obtained by attaching four [RuII(bipy)2Cl] groups to the pyridyl substituents of meso-tetra(4-pyridyl)porphyrin and its metallated derivatives. These compounds display a rich electrochemistry and versatile catalytic, electrocatalytic and photochemical p...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/s0001-37652000000100003
更新日期：2000-01-01 00:00:00
abstract：:Eimeriosis is caused by a protozoan parasite of the genus Eimeria and infection affecting most domestic animal species. The aim of this research was to comprehend the impact of selenium nanoparticles (SeNPs) on eimeriosis induced by Eimeria papillata in mouse jejunum, and how they work as antioxidants and anti-apoptot...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/0001-3765202020191107
更新日期：2020-06-03 00:00:00
abstract：:In the Budgerigar Melopsittacus undulatus, the significance of a conspecific alarm call was investigated in two seasons, winter and spring. Two qualitatively different behavioral responses were displayed by the receivers in reply to playbacks: call(s) and/or taking flight(s). The comparative analysis of the number of ...
journal_title：Anais da Academia Brasileira de Ciencias
pub_type： 杂志文章
doi：10.1590/s0001-37652004000200025
更新日期：2004-06-01 00:00:00
