Acidólisis enzimática de trioleina con los ácidos palmítico y caprílico: Optimización de los parámetros de la reacción mediante la metodología de superficie de respuesta

An acidolysis reaction of triolein with caprylic and palmitic acids was performed using immobilized sn-1,3 specific lipase from Mucor miehei to produce a reduced calorie spreadable structured lipid (SL). Response surface methodology was applied to model and optimize the reaction conditions using a four-factor five-level central composite rotatable design. The selected factors were time (10-24 h), enzyme load (10-25 wt%), substrate mole ratio (Triolein:Caprylic acid:Palmitic acid), (1:1:1-1:2.5:2.5) and temperature (45-60 °C). The produced SLs were compared to fat extracts of commercial margarine in terms of melting profile and solid fat content (SFC). SL with a melting peak of 42 °C and SFC of 40.69% at 0 °C was very similar to soft margarines. The caloric value of this SL was determined as 37.74 kJ/g, theoretically. The optimum reaction conditions were found as reaction time 14 h; substrate mole ratio 1:2.1:2.1; temperature 58 °C; and enzyme load 15 wt%. Under optimum conditions, the product contained 29.68% COC, 25.47% POC, and 3.80% POP.La reacción de acidolísis de la trioleina con los ácidos caprílico y palmítico se realizó utilizando lipasa inmovilizada Mucor miehei, específica de sn-1, 3, para producir una grasa de untar baja en calorías compuesta de lípidos estructurados (SL). La metodología de superficie de respuesta se aplica para modelar y optimizar las condiciones de reacción utilizando un factor-cuatro y nivel-cinco de diseño central compuesto. Los factores seleccionados fueron el tiempo (10-24 h), la carga de enzima (10-25% en peso), la relación molar de sustratos (Trioleína:Ácido Caprílico:Ácido Palmítico), (1:1:1-1:2.5:2.5) y la temperatura (45-60 °C). Los SLs producidos se compararon con extractos de grasa de margarina comercial en términos de perfil de fusión y contenido de grasa sólida (SFC). El SL con un pico de fusión a 42 °C y SFC de 40,69% a 0 °C era muy similar a las margarinas suaves. El valor calórico de este SL se determinó teóricamente siendo 37,74 kJ/g. Las condiciones óptimas de reacción encontradas fueron 14 h de tiempo de reacción; una relación molar de sustratos 1:2.1:2.1; una temperatura de 58 °C, y una carga enzima de 15% en peso. En condiciones óptimas el producto contenía 29,68% de AOC, 25,47% de POC, y 3,80% de POP

Extracción asistida por microondas de compuestos no polares de cáscaras de pistacho y caracterización de los extractos

Soxhlet and microwave assisted extraction (MAE) methods were used to obtain non-polar compounds from pistachio hull. MAE parameters (liquid to solid ratio, microwave power, and extraction time) were studied to obtain maximum extraction yield. The optimal conditions were found to be liquid to solid ratio of 15:1 (v/w), microwave power of 250 W and extraction time of 12.5 min. The extraction yields were 9.81 and 9.50% for MAE and Soxhlet methods, respectively. The total phenolic content, antioxidant activity and tocopherol content of the extract obtained by MAE was found to be significantly higher than those of the Soxhlet extract (p < 0.05). The results showed that the extract contained α-tocopherols (567.65 mg/kg) and oleic acid (48.46%) as the major tocopherols and fatty acids. These findings propose that hull extracts can be considered as a good source of natural bioactive compounds and MAE can be a good alternative to the traditional Soxhlet method.Se utilizó la extracción mediante Soxhlet y métodos de extracción asistida mediante microondas (MAE) para obtener compuestos no polares de las cascaras de pistacho. Se estudiaron los parámetros para la MAE (relación líquido-sólido, potencia de microondas y tiempo de extracción) para obtener el máximo rendimiento de la extracción. Se encontró que las condiciones óptimas eran una relación líquido a sólido de 15:1 (v/p), potencia de microondas de 250 W y un tiempo de extracción de 12,5 minutos. Los rendimientos de extracción fueron 9.81 y 9.50% para los métodos MAE y Soxhlet, respectivamente. El contenido fenólico total, la actividad antioxidante y el contenido de tocoferoles de los extractos obtenidos por MAE fueron significativamente más altos que los de los extractos de Soxhlet (p < 0,05). Los resultados muestran que el extracto contiene α-tocoferol (567.65 mg/kg) y ácido oleico (48.46%) como los principales tocoferoles y ácidos grasos, respectivamente. Estos hallazgos proponen que los extractos de las cascaras pueden considerarse como una buena fuente de compuestos bioactivos naturales y MAE puede ser una buena alternativa al método Soxhlet tradicional

Acidolisis de aceite de pistacho con los ácidos palmítico y caprílico en un reactor de recirculación de lecho compacto: optimización mediante metodología de superficie de respuesta

The acidolysis reaction of terebinth fruit oil with caprylic and palmitic acid has been investigated. The reaction was catalyzed by lipase (Lipozyme IM from Rhizomucormiehei) and carried out in recirculating packed bed reactor. The effects of reaction parameters have been analyzed using response surface methodology. Reaction time (3.5–6.5 h), enzyme load (10–20%), substrate flow rate (4–8 mL·min-1) and substrate mole ratios (Terebinth oil : Palmitic acid : Caprylic acid, 1:1.83:1.22–1:3.07:2.05) were evaluated. The optimum reaction conditions were 5.9 h reaction time, 10% enzyme load, 4 mL·min-1 substrate flow rate and 1:3.10:2.07 substrate mole ratio. The structured lipid obtained at these optimum conditions had 52.23% desired triacylglycerols and a lower caloric value than that of terebinth fruit oil. The melting characteristics and microstructure of the structured lipid were similar to those of commercial margarine fat extracts. The results showed that the structured lipid had the highest oxidative stability among the studied fats.Se ha investigado la reacción de acidolisis del aceite de pistacho con los ácidoscaprílico y palmítico. La reacción fue catalizada por la lipasa Lipozyme IM de Rhizomucormiehei y realizada mediante recirculación del reactor de lecho compacto. Los efectos de los parámetros de la reacción han sido analizados mediante el uso de la metodología de superficie de respuesta. El tiempo de reacción (3.5 hasta 6.5 h), la carga de enzima (10–20%), el caudal de sustrato (4–8 mL·min-1) relaciones molares de los sustrato (aceite de pistacho: ácido palmítico: ácido caprílico, 1: 1,83: 1,22–1: 3,07: 2,05) fueron evaluados. Las condiciones óptimas de reacción fueron 5,9 h de tiempo de reacción, el 10% de carga de la enzima, 4 mL·min-1 de caudal de sustrato y 1: 3,10: 2,07 de relación molar de sustratos. Los lípidos estructurados obtenidos en las condiciones óptimas tenías 52,23% de triacilgliceroles deseados y un valor calórico menor que la de encina aceite de la fruta. Características de fusión y microestructura de lípido estructurado fueron similares a las de los extractos de grasa margarina comerciales. Los resultados mostraron que el lípido estructurado tenía una estabilidad oxidativa más alta entre las grasas estudiadas

A wideband linear tunable CDTA and its application in field programmable analogue array

This document is the Accepted Manuscript version of the following article: Hu, Z., Wang, C., Sun, J. et al. ‘A wideband linear tunable CDTA and its application in field programmable analogue array’, Analog Integrated Circuits and Signal Processing, Vol. 88 (3): 465-483, September 2016. Under embargo. Embargo end date: 6 June 2017. The final publication is available at Springer via https://link.springer.com/article/10.1007%2Fs10470-016-0772-7 © Springer Science+Business Media New York 2016In this paper, a NMOS-based wideband low power and linear tunable transconductance current differencing transconductance amplifier (CDTA) is presented. Based on the NMOS CDTA, a novel simple and easily reconfigurable configurable analogue block (CAB) is designed. Moreover, using the novel CAB, a simple and versatile butterfly-shaped FPAA structure is introduced. The FPAA consists of six identical CABs, and it could realize six order current-mode low pass filter, second order current-mode universal filter, current-mode quadrature oscillator, current-mode multi-phase oscillator and current-mode multiplier for analog signal processing. The Cadence IC Design Tools 5.1.41 post-layout simulation and measurement results are included to confirm the theory.Peer reviewedFinal Accepted Versio

Acidolysis of terebinth fruit oil with palmitic and caprylic acids in a recirculating packed bed reactor: optimization using response surface methodology

The acidolysis reaction of terebinth fruit oil with caprylic and palmitic acid has been investigated. The reaction was catalyzed by lipase (Lipozyme IM from <em>Rhizomucormiehei</em>) and carried out in recirculating packed bed reactor. The effects of reaction parameters have been analyzed using response surface methodology. Reaction time (3.5–6.5 h), enzyme load (10–20%), substrate flow rate (4–8 mL·min^-1) and substrate mole ratios (Terebinth oil : Palmitic acid : Caprylic acid, 1:1.83:1.22–1:3.07:2.05) were evaluated. The optimum reaction conditions were 5.9 h reaction time, 10% enzyme load, 4 mL·min^-1 substrate flow rate and 1:3.10:2.07 substrate mole ratio. The structured lipid obtained at these optimum conditions had 52.23% desired triacylglycerols and a lower caloric value than that of terebinth fruit oil. The melting characteristics and microstructure of the structured lipid were similar to those of commercial margarine fat extracts. The results showed that the structured lipid had the highest oxidative stability among the studied fats.<br><br>Se ha investigado la reacción de acidolisis del aceite de pistacho con los ácidoscaprílico y palmítico. La reacción fue catalizada por la lipasa Lipozyme IM de <em>Rhizomucormiehei</em> y realizada mediante recirculación del reactor de lecho compacto. Los efectos de los parámetros de la reacción han sido analizados mediante el uso de la metodología de superficie de respuesta. El tiempo de reacción (3.5 hasta 6.5 h), la carga de enzima (10–20%), el caudal de sustrato (4–8 mL·min^-1) relaciones molares de los sustrato (aceite de pistacho: ácido palmítico: ácido caprílico, 1: 1,83: 1,22–1: 3,07: 2,05) fueron evaluados. Las condiciones óptimas de reacción fueron 5,9 h de tiempo de reacción, el 10% de carga de la enzima, 4 mL·min^-1 de caudal de sustrato y 1: 3,10: 2,07 de relación molar de sustratos. Los lípidos estructurados obtenidos en las condiciones óptimas tenías 52,23% de triacilgliceroles deseados y un valor calórico menor que la de encina aceite de la fruta. Características de fusión y microestructura de lípido estructurado fueron similares a las de los extractos de grasa margarina comerciales. Los resultados mostraron que el lípido estructurado tenía una estabilidad oxidativa más alta entre las grasas estudiadas

Mean-Field HP Model, Designability and Alpha-Helices in Protein Structures

Analysis of the geometric properties of a mean-field HP model on a square lattice for protein structure shows that structures with large number of switch backs between surface and core sites are chosen favorably by peptides as unique ground states. Global comparison of model (binary) peptide sequences with concatenated (binary) protein sequences listed in the Protein Data Bank and the Dali Domain Dictionary indicates that the highest correlation occurs between model peptides choosing the favored structures and those portions of protein sequences containing alpha-helices.Comment: 4 pages, 2 figure

Specialized dynamical properties of promiscuous residues revealed by simulated conformational ensembles

The ability to interact with different partners is one of the most important features in proteins. Proteins that bind a large number of partners (hubs) have been often associated with intrinsic disorder. However, many examples exist of hubs with an ordered structure, and evidence of a general mechanism promoting promiscuity in ordered proteins is still elusive. An intriguing hypothesis is that promiscuous binding sites have specific dynamical properties, distinct from the rest of the interface and pre-existing in the protein isolated state. Here, we present the first comprehensive study of the intrinsic dynamics of promiscuous residues in a large protein data set. Different computational methods, from coarse-grained elastic models to geometry-based sampling methods and to full-atom Molecular Dynamics simulations, were used to generate conformational ensembles for the isolated proteins. The flexibility and dynamic correlations of interface residues with a different degree of binding promiscuity were calculated and compared considering side chain and backbone motions, the latter both on a local and on a global scale. The study revealed that (a) promiscuous residues tend to be more flexible than nonpromiscuous ones, (b) this additional flexibility has a higher degree of organization, and (c) evolutionary conservation and binding promiscuity have opposite effects on intrinsic dynamics. Findings on simulated ensembles were also validated on ensembles of experimental structures extracted from the Protein Data Bank (PDB). Additionally, the low occurrence of single nucleotide polymorphisms observed for promiscuous residues indicated a tendency to preserve binding diversity at these positions. A case study on two ubiquitin-like proteins exemplifies how binding promiscuity in evolutionary related proteins can be modulated by the fine-tuning of the interface dynamics. The interplay between promiscuity and flexibility highlighted here can inspire new directions in protein-protein interaction prediction and design methods. © 2013 American Chemical Society

Protein sequence and structure: Is one more fundamental than the other?

We argue that protein native state structures reside in a novel "phase" of matter which confers on proteins their many amazing characteristics. This phase arises from the common features of all globular proteins and is characterized by a sequence-independent free energy landscape with relatively few low energy minima with funnel-like character. The choice of a sequence that fits well into one of these predetermined structures facilitates rapid and cooperative folding. Our model calculations show that this novel phase facilitates the formation of an efficient route for sequence design starting from random peptides.Comment: 7 pages, 4 figures, to appear in J. Stat. Phy

Composite structural motifs of binding sites for delineating biological functions of proteins

Most biological processes are described as a series of interactions between proteins and other molecules, and interactions are in turn described in terms of atomic structures. To annotate protein functions as sets of interaction states at atomic resolution, and thereby to better understand the relation between protein interactions and biological functions, we conducted exhaustive all-against-all atomic structure comparisons of all known binding sites for ligands including small molecules, proteins and nucleic acids, and identified recurring elementary motifs. By integrating the elementary motifs associated with each subunit, we defined composite motifs which represent context-dependent combinations of elementary motifs. It is demonstrated that function similarity can be better inferred from composite motif similarity compared to the similarity of protein sequences or of individual binding sites. By integrating the composite motifs associated with each protein function, we define meta-composite motifs each of which is regarded as a time-independent diagrammatic representation of a biological process. It is shown that meta-composite motifs provide richer annotations of biological processes than sequence clusters. The present results serve as a basis for bridging atomic structures to higher-order biological phenomena by classification and integration of binding site structures.Comment: 34 pages, 7 figure