Mode of operation and low-resolution structure of a multi-domain and hyperthermophilic endo-beta-1,3-glucanase from Thermotoga petrophila

1,3-beta-Glucan depolymerizing enzymes have considerable biotechnological applications including biofuel production, feedstock-chemicals and pharmaceuticals. Here we describe a comprehensive functional characterization and low-resolution structure of a hyperthermophilic laminarinase from Thermotoga petrophila (TpLam). We determine TpLam enzymatic mode of operation, which specifically cleaves internal beta-1,3-glucosidic bonds. The enzyme most frequently attacks the bond between the 3rd and 4th residue from the non-reducing end, producing glucose, laminaribiose and laminaritriose as major products. Far-UV circular dichroism demonstrates that TpLam is formed mainly by beta structural elements, and the secondary structure is maintained after incubation at 90 degrees C. The structure resolved by small angle X-ray scattering, reveals a multi-domain structural architecture of a V-shape envelope with a catalytic domain flanked by two carbohydrate-binding modules. Crown Copyright (C) 2011 Published by Elsevier Inc. All rights reserved.

Menezesite, the first natural heteropolyniobate, from Cajati, Sao Paulo, Brazil: Description and crystal structure

Menezesite, ideally Ba2MgZr4(BaNb12O42)center dot 12H(2)O, occurs as a vug mineral in the contact zone between dolomite carbonatite and ""jacupirangite"" (=a pyroxenite) at the Jacupiranga mine, in Cajati county, Sao Paulo state, Brazil, associated with dolomite, calcite, magnetite, clinohumite, phlogopite, ancylite-(Ce), strontianite, pyrite, and tochilinite. This is also the type locality for quintinite-2H. The mineral forms rhombododecahedra up to I mm, isolated or in aggregates. Menezesite is transparent and displays a vitreous luster; it is reddish brown with a white streak. It is non-fluorescent. Mohs hardness is about 4. Calculated density derived from the empirical formula is 4.181 g/cm(3). It is isotropic, 1.93(1) (white light); n(calc) = 2.034. Menezesite exhibits weak anomalous birefringence. The empirical formula is (Ba1.47K0.53Ca0.3,Ce0.17Nd0.10Na0.06La0.02)(Sigma 2.66)(Mg0.94Mn0.23Fe0.23Al0.03)(Sigma 1.43)(Zr2.75Ti0.96Th0.29)(Sigma 4.00)[(Ba0.72Th0.26U0.02)(Sigma 1.00)(Nb9.23Ti2.29Ta0.36Si0.12)Sigma O-12.00(42)]center dot 12H(2)O. The mineral is cubic, space group 10 (204), a = 13.017(1) angstrom, V = 2206(1) angstrom(3), Z = 2. Menezesite is isostructural with the synthetic compound Mg-7[MgW12O42](OH)(4)center dot 8H(2)O. The mineral was named in honor of Luiz Alberto Dias Menezes Filho (born 1950), mining engineer, mineral collector and merchant. Both the description and the name were approved by the CNMMN-IMA (Nomenclature Proposal 2005-023). Menezesite is the first natural heteropolyniobate. Heteropolyanions have been employed in a range of applications that include virus-binding inorganic drugs (including the AIDs virus), homogeneous and heterogeneous catalysts, electro-optic and electrochromic materials, metal and protein binding, and as building blocks for nanostructuring of materials.

THE CRYSTAL STRUCTURE OF A MICROLITE-GROUP MINERAL WITH A FORMULA NEAR NaCaTa(2)O(6)F FROM THE MORRO REDONDO MINE, CORONEL MURTA, MINAS GERAIS, BRAZIL

We present electron-microprobe and single-crystal X-ray-diffraction data for a microlite-group mineral with a formula near NaCaTa(2)O(6)F from the Morro Redondo mine, Coronel Murta, Minas Gerais, Brazil. On the basis of these data, the formula is A(Na(0.88)Ca(0.88)Pb(0.02)square(0.22))(Sigma 2.00) (B)(Ta(1.70)Nb(0.14)Si(0.12)As(0.04))(Sigma 2.00) (X)[(O(5.75)(OH)(0.25)](Sigma 6.00) (Y)(F(0.73)square(0.27))(Sigma 1.00). According to the new nomenclature for the pyrochlore-supergroup minerals, it is intermediate between fluornatromicrolite and "" fluorcalciomicrolite"". The crystal structure, F (d3) over barm, a = 10.4396(12) angstrom, has been refined to an R(1) value of 0.0258 (wR(2) = 0.0715) for 107 reflections (MoK alpha radiation). There is a scarcity of crystal-chemical data for pyrochlore-supergroup minerals in the literature. A compilation of these data is presented here.

Timing and structure of the 8.2 kyr BP event inferred from delta(18)O records of stalagmites from China, Oman, and Brazil

Oxygen isotope records of stalagmites from China and Oman reveal a weak summer monsoon event, with a double-plunging structure, that started 8.21 +/- 0.02 kyr B. P. An identical but antiphased pattern is also evident in two stalagmite records from eastern Brazil, indicating that the South American Summer Monsoon was intensified during the 8.2 kyr B. P. event. These records demonstrate that the event was of global extent and synchronous within dating errors of <50 years. In comparison with recent model simulations, it is plausible that the 8.2 kyr B. P. event can be tied in changes of the Atlantic Meridional Overturning Circulation triggered by a glacial lake draining event. This, in turn, affected North Atlantic climate and latitudinal position of the Intertropical Convergence Zone, resulting in the observed low-latitude monsoonal precipitation patterns.

Structure, processing and midgut secretion of putative peritrophic membrane ancillary protein (PMAP) from Tenebrio molitor larvae

A cDNA coding for a Tenebrio molitor midgut protein named peritrophic membrane ancillary protein (PMAP) was cloned and sequenced. The complete cDNA codes for a protein of 595 amino acids with six insect-allergen-related-repeats that may be grouped in A (predicted globular)- and B (predicted nonglobular)-types forming an ABABAB structure. The PMAP-cDNA was expressed in Pichia pastoris and the recombinant protein (64 kDa) was purified to homogeneity and used to raise antibodies in rabbits. The specific antibody detected PMAP peptides (22 kDa) in the anterior and middle midgut tissue, luminal contents, peritrophic membrane and feces. These peptides derive from PMAP, as supported by mass spectrometry, and resemble those formed by the in vitro action of trypsin on recombinant PMAP. Both in vitro and in vivo PMAP processing seem to occur by attack of trypsin to susceptible bonds in the coils predicted to link AB pairs, thus releasing the putative functional AB structures. The AB-domain structure of PMAP is found in homologous proteins from several insect orders, except lepidopterans that have the apparently derived protein known as nitrile-specifier protein. Immunocytolocalization shows that PMAP is secreted by exocytosis and becomes entrapped in the glycocalyx, before being released into midgut contents. Circumstantial evidence suggests that PMAP-like proteins have a role in peritrophic membrane type 2 formation. (C) 2007 Elsevier Ltd. All rights reserved.

Relationship between structure and photoactivity of porphyrins derived from protoporphyrin IX

Protoporphyrin (Pp IX) derivatives were prepared to study the relationship between photosensitizer structure and photoactivity, with an emphasis on understanding the role of membrane interactions in the efficiency of photosensitizers used in photodynamic therapy (PDT). The synthetic strategies described here aimed at changing protoporphyrin periferic groups, varying overall charge and oil/water partition, while maintaining their photochemical properties. Three synthetic routes were used: (1) modification of Pp IX at positions 3(1) and 8(1) by addition of alkyl amine groups of different lengths (compounds 2-5), (2) change of Pp IX at positions 13(3) and 17(3), generating alkyl amines (compounds 6 and 7), a phosphate amine (compound 8), and quarternary ammonium compounds (compounds 9 and 10), and (3) amine-alkylation of Hematoporphyrin IX (Hp IX) at positions 3(1), 8(1), 13(3) and 17(3) (compound 12). Strategy 1 leads to hydrophobic compounds with low photocytotoxicity. Strategy 2 leads to compounds 6-10 that have high levels of binding/incorporation in vesicles, mitochondria and cells, which are indicative of high bioavailability. Addition of the phosphate group (compound 8), generates an anionic compound that has low liposome and cell incorporation, plus low photocytotoxicity. Compound 12 has intermediate incorporation and photocytotoxic properties. Compound modification is also associated with changes in their sub-cellular localization: 30% of 8 (anionic) is found in mitochondria as compared to 95% of compound 10 (cationic). Photocytotoxicity was shown to be highly correlated with membrane affinity, which depends on the asymmetrical and amphiphilic characters of sens, as well as with sub-cellular localization.

Calculating Flash Point Numbers from Molecular Structure: An Improved Method for Predicting the Flash Points of Acyclic Alkanes

We report a novel method for calculating flash points of acyclic alkanes from flash point numbers, N(FP), which can be calculated from experimental or calculated boiling point numbers (Y(BP)) with the equation N(FP) = 1.020Y(BP) - 1.083 Flash points (FP) are then determined from the relationship FP(K) = 23.369N(FP)(2/3) + 20.010N(FP)(1/3) + 31.901 For it data set of 102 linear and branched alkanes, the correlation of literature and predicted flash points has R(2) = 0.985 and an average absolute deviation of 3.38 K. N(FP) values can also be estimated directly from molecular structure to produce an even closer correspondence of literature and predicted FP values. Furthermore, N(FP) values provide a new method to evaluate the reliability of literature flash point data.

Translating text into motion : performance analysis for singers and directors

The study proposes a method of interpretation, which gives the contemporary singer-actor and director a method of performance analysis considering both the visual and the auditory aspects of vocal performance. The analysis begins with an analysis of the structure, which maps out the key ideas and translates them into main states of mind. The text analysis is followed by an analysis of the musical treatment of the text, also scanning for extra dramatic meaning inherent in vocal line and musical accompaniment. The so isolated dramatic ideas in text and musical structure and content are finally discussed in terms of their physical aspects, using the system of gesture as practiced by actors and singers before, during and beyond the Baroque period. The method is exemplified by the obbligato recitative "In quali eccessi" from Donna Elvira’s scene in the second act of the opera "Don Giovanni" by L. Da Ponte and W. A. Mozart. The musical example includes gestural notation and a table gestural notation symbols.

Revisiting capital structure theory : a test of pecking order and static order trade-of model from Malaysian capital market

This study revisits the capital structure theory and test Pecking Order Hypothesis (POH) and Static Order Trade-off theory (STOT) using Malaysian Listed firms over a period from 1999 to 2002. The evidence from pecking order model suggests that the internal fund deficiency is the most important determinant that possibly explains the issuance of new debt in Malaysian capital market despite the lower predicting power.  While static trade off-model is not fit to explain the issuance of new debt issue in Malaysian capital market. This is an interesting findings that confirm the fact that Malaysian firms do not too much care about tax-shield benefit derive from employ both debt and non-debt tax-shield. The finn's size, which is used to neutralize the size effect, appears to provide some explanation for the variation in its capital structure policy choice; however asset structure and growth no evidence of static-order-trade-off is observed in Malaysian capital market.

Board structure and firm performance : evidence from India's top 500 companies

The objective of this paper is to investigate the relationship between internal governance structures in Indian companies and financial performance. The
study includes an examination of aspects of the effectiveness of boards of directors', including composition of the board, board size and aspects of board leadership including duality and board busyness.

Probing the flexibility of the DsbA oxidoreductase from Vibrio cholerae - a 15N -1H heteronuclear NMR relaxation analysis of oxidised and reduced forms of DsbA

We have determined the structure of the reduced form of the DsbA oxidoreductase from Vibrio cholerae. The reduced structure shows a high level of similarity to the crystal structure of the oxidized form and is typical of this class of enzyme containing a thioredoxin domain with an inserted α-helical domain. Proteolytic and thermal stability measurements show that the reduced form of DsbA is considerably more stable than the oxidized form. NMR relaxation data have been collected and analyzed using a model-free approach to probe the dynamics of the reduced and oxidized states of DsbA. Akaike's information criteria have been applied both in the selection of the model-free models and the diffusion tensors that describe the global motions of each redox form. Analysis of the dynamics reveals that the oxidized protein shows increased disorder on the pico- to nanosecond and micro- to millisecond timescale. Many significant changes in dynamics are located either close to the active site or at the insertion points between the domains. In addition, analysis of the diffusion data shows there is a clear difference in the degree of interdomain movement between oxidized and reduced DsbA with the oxidized form being the more rigid. Principal components analysis has been employed to indicate possible concerted movements in the DsbA structure, which suggests that the modeled interdomain motions affect the catalytic cleft of the enzyme. Taken together, these data provide compelling evidence of a role for dynamics in the catalytic cycle of DsbA.

Structure, people and process challenges of mutichannel marketing : insights from marketers

The aim of this study was to explore the utility of strategic implementation theory as a guide for dealing with issues marketers face when implementing multichannel marketing. Although marketers attempt to harness the potential of emerging marketing channels, implementation is proving difficult. This is because the complexity of multichannel marketing has implications for existing organisational structures, people and processes. Further, the reliance on external suppliers and vendors in implementing new channels is causing organisational conflict and the development of new management processes. A qualitative research approach using insights from senior marketers of 'Bluechip' organisations was used to identify multichannel marketing implementation difficulties. The major contribution of this article was to show the areas for which strategic implementation theory provides practical implementation guidelines and future research directions.

Board structure and firm performance : evidence from India's top companies

Manuscript Type: Empirical

Research Question/Issue: This paper investigates the relationship between internal governance structures and financial performance of Indian companies. The effectiveness of boards of directors, including board composition, board size, and aspects of board leadership including duality and board busyness are addressed in the Indian context using two theories of corporate governance: agency theory and resource dependency theory.

Research Findings/Insights: The study used a sample of top Indian companies taking into account the endogeneity of the relationships among corporate governance, corporate performance, and corporate capital structure. The study provides some support for aspects of agency theory as a greater proportion of outside directors on boards were associated with improved firm performance. The notion of separating leadership roles in a manner consistent with agency theory was not supported. For instance, the notion that powerful CEOs (duality role, CEO being the promoter, and CEO being the only board manager) have a detrimental effect on performance was not supported. There was some support for resource dependency theory. The findings suggest that larger board size has a positive impact on performance thus supporting the view that greater exposure to the external environment improves access to various resources and thus positively impacts on performance. The study however failed to support the resource dependency theory in terms of the association between frequency of board meetings and performance. Similarly the results showed that outside directors with multiple appointments appeared to have a negative effect on performance, suggesting that "busyness" did not add value in terms of networks and enhancement of resource accessibility.

Theoretical/Academic Implications: The two theories of corporate governance, namely agency and resource dependence theory, were each only partially supported, by the findings of this study. The findings add further to the view that no single theory explains the nexus between corporate governance and performance.

Practitioner/Policy Implications: This study demonstrates that corporate governance measures utilized in developed economies related to boards of directors have some synergies and relevance to emerging economies, such as India. However, the nature of business structures in India, for example the large number of family businesses, may limit the generalizability of the findings and signals the need for further investigation of these businesses. The evidence related to multiple appointments of directors suggests that there may be support for restricting the number of directorships held by any one individual in emerging economies, given that the "busyness" of directors was negatively associated with firm performance.

The impact of ownership structure on corporate debt policy : two stage least square simultaneous model approach for post crisis period : evidence from Kuala Lumpur Stock Exchange

Ownership concentration as a governance mechanism has received considerable attention among academician, practitioners as well as policy makers because large-block shareholders are increasingly active in their demands that corporations adopt effective governance mechanisms to control managerial decisions, which include corporate debt policy. Earlier study on the agency model of the firm widely recognizes that the managerial ownership and external debt play an important role in mitigating agency conflicts and enhancing firm value. They also found that increase in the external monitors, for example the institutional investors, can actually play a useful role in limiting agency problems in the firm. This paper, using 100 Composite Index companies from Brusa Malaysia between 1998 to 2002 explores the impact of institutional holdings on managerial ownership and debt policy in an integrated framework by using a simultaneous equations estimation procedure (2SLS). The findings show that there is a significant impact of institutional ownership which serves effective control mechanism on managerial ownership and corporate debt policy as hypothesized. Findings of such evidence suggest that institutional holding thus have played an important role in managers' strategic management decision and reduce agency conflict. In addition, corporate debt policy too is governed by managerial ownership and exhibited a negative relation.