RESUMO
BACKGROUND: Pea, lentil, faba bean, chickpea and bean proteins are potentially renewable raw materials for bioplastic production that can be obtained from agricultural waste. Plastics are usually processed under heating, and thus thermal stability is a mandatory requirement for the application. In this study, the thermal behavior of several legume protein isolates at different purity degrees was investigated. RESULTS: The thermal stability of proteins extracted from legumes was maximum for chickpeas and minimum for beans and decreased with decreasing protein purity in the range 30-88%. A similar dependence on purity was observed for the glass transition temperature. On the contrary, the denaturation temperature was found not to depend on sample purity and origin and was lower than the degradation temperature only in the case of protein samples with purity higher than 60%. CONCLUSION: Proteins from legumes are suitable to produce thermoplastic biopolymeric materials if isolated at purity higher than 60%. In fact, under this circumstance, they can be denaturized without degrading and thus are suitable for extrusion processing. © 2018 Society of Chemical Industry.
Assuntos
Fabaceae/química , Proteínas de Plantas/química , Varredura Diferencial de Calorimetria , Fabaceae/classificação , Temperatura Alta , Desnaturação Proteica , Espectroscopia de Infravermelho com Transformada de Fourier , TermogravimetriaRESUMO
A new amperometric immunosensor based on the covalent immobilization of tissue transglutaminase enzyme in its open conformation (open-tTG) was developed and optimized for determination of anti-tissue transglutaminase antibodies (anti-tTG) in human serum. Experimental design allowed us to find the optimal conditions for quantification of both IgA and IgG isotypes of anti-tTG in order to assess suitability of the device for diagnostic purposes. The glassy carbon electrodic substrate was electrochemically functionalized with gold nanoparticles and subsequently derivatized with a self-assembled monolayer of 11-mercaptoundecanoic acid for the covalent anchoring of the enzyme. This step was performed under carefully controlled conditions in order to keep the open conformation of the tTG. The immunosensor showed good analytical performance with limit of detection levels (1.7 AU mL(-1) for IgA and 2.7 AU mL(-1) for IgG) below the diagnostic threshold value (3.0 AU mL(-1)) and inter-sensor reproducibility giving RSD lower than 10%. The developed sensor was validated in serum samples from pediatric patients for clinical applications, using two ELISA kits specific for the determination of anti-tTG IgA and IgG antibodies as reference methods; good recovery rates ranging from 74% to 117% were calculated.
Assuntos
Autoanticorpos/sangue , Técnicas Biossensoriais/métodos , Doença Celíaca/diagnóstico , Proteínas de Ligação ao GTP/imunologia , Transglutaminases/imunologia , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/estatística & dados numéricos , Doença Celíaca/enzimologia , Doença Celíaca/imunologia , Criança , Técnicas Eletroquímicas , Ensaio de Imunoadsorção Enzimática , Enzimas Imobilizadas/química , Enzimas Imobilizadas/imunologia , Ácidos Graxos , Proteínas de Ligação ao GTP/química , Ouro , Humanos , Imunoglobulina A/sangue , Imunoglobulina G/sangue , Limite de Detecção , Nanopartículas Metálicas , Conformação Proteica , Proteína 2 Glutamina gama-Glutamiltransferase , Reprodutibilidade dos Testes , Compostos de Sulfidrila , Transglutaminases/químicaRESUMO
A new voltammetric competitive immunosensor selective for atrazine, based on the immobilization of a conjugate atrazine-bovine serum albumine on a nanostructured gold substrate previously functionalized with poliamidoaminic dendrimers, was realized, characterized, and validated in different real samples of environmental and food concern. Response of the sensor was reliable, highly selective and suitable for the detection and quantification of atrazine at trace levels in complex matrices such as territorial waters, corn-cultivated soils, corn-containing poultry and bovine feeds and corn flakes for human use. Selectivity studies were focused on desethylatrazine, the principal metabolite generated by long-term microbiological degradation of atrazine, terbutylazine-2-hydroxy and simazine as potential interferents. The response of the developed immunosensor for atrazine was explored over the 10(-2)-10(3) ng mL(-1) range. Good sensitivity was proved, as limit of detection and limit of quantitation of 1.2 and 5 ng mL(-1), respectively, were estimated for atrazine. RSD values <5% over the entire explored range attested a good precision of the device.
