RESUMO -O maracujá (Passiflora edulis) é originário da América Tropical, muito cultivado no Brasil, rico em vitamina C, cálcio e fósforo. Cascas e sementes de maracujá, provenientes do processo de corte e extração da fruta para obtenção do suco, são ainda, atualmente, em grande parte descartadas. Como este descarte representa inúmeras toneladas, agregar valor a estes subprodutos é de interesse econômico, científico e tecnológico. Neste trabalho, realizou-se um estudo para caracterizar e verificar um melhor aproveitamento das sementes excedentes do processamento do suco do maracujá na alimentação humana. Procedeu-se, para tanto, à separação das partes da fruta, com posterior quantificação gravimétrica. As sementes obtidas foram secas em estufa, e posteriormente moídas para a obtenção de um farelo. O óleo do farelo obtido foi extraído em soxhlet e caracterizado através da metodologia oficial da AOCS (1995). O farelo desengordurado obtido foi também caracterizado por métodos físico-químicos, através da determinação do teor de umidade, proteínas, lipídeos, fibras, cinzas e carboidratos por metodologia oficial AOAC (1984). O óleo extraído das sementes apresentou elevado teor de ácidos graxos insaturados (87,54%), com predominância do ácido linoléico, com índice de iodo de 136,5g I 2 /100g. O farelo desengordurado obtido apresentou teor da 10,53% de umidade; 15,62% de proteínas; 0,68% de lipídeos; 1,8% de cinzas, um elevado teor de fibras de 58,98 e 12,39% de carboidratos. Termos para indexação: Óleo de semente, descarte, subprodutos. CHARACTERIZATION OF BY-PRODUCTS OF PASSION FRUIT INDUSTRIALIZATION UTILIZATION OF SEEDSABSTRACT -The passion fruit (Passiflora edulis) is originary from Tropical America and has been growing largely in Brazil, being a crop very rich in vitamin C, calcium and phosphorus. Peels and seeds of Passion fruit that come from the cut and extraction process of fruit in order to extract juice are still throw out in large amounts. As such amounts depict lots tons, ascribing values to the by-products is of great economical, scientific and technological interest. The aim of the current manuscript is to characterize a better utilization of seeds deriving from the processing of passion fruit juice for human nutrition. For that, a separation procedure for different parts of the fruit with gravimetric quantification has been adopted. The obtained seeds were dried in stove and afterwards grounded for obtaining the bran. The oil of the obtained bran was extracted with hexane and characterized by means of an official methodology proposed by AOCS (1995). The non greased bran has also been characterized by physical-chemical methods, through determination of the moisture, protein, lipid, fiber, ashes and carbohydrates contents based on the official methodology recommended by the AOAC (1984). The oil extracted from the seeds showed high levels of unsaturated fatty acid (87.54%), with a predominance of the linoleic acid, whose iodine index was of 136.5g I 2 /100g. The non greased bran showed contents of moisture,...

Aiming to contribute toward the characterization of new, biotechnologically relevant cellulolytic enzymes, we report here the first crystal structure of the catalytic core domain of Cel7A (cellobiohydrolase I) from the filamentous fungus Trichoderma harzianum IOC 3844. Our structural studies and molecular dynamics simulations show that the flexibility of Tyr260, in comparison with Tyr247 from the homologous Trichoderma reesei Cel7A, is enhanced as a result of the short side‐chains of adjacent Val216 and Ala384 residues and creates an additional gap at the side face of the catalytic tunnel. T. harzianum cellobiohydrolase I also has a shortened loop at the entrance of the cellulose‐binding tunnel, which has been described to interact with the substrate in T. reesei Cel7A. These structural features might explain why T. harzianum Cel7A displays higher kcat and Km values, and lower product inhibition on both glucoside and lactoside substrates, compared with T. reesei Cel7A.

Background: Substrate interactions in the long tunnel of processive cellulases govern both their catalytic activity and stepwise movement along a cellulose strand. Results: The energetics of enzyme-substrate interactions at different depths of the tunnel are reported. Conclusion:The affinity for the substrate varies strongly through the tunnel. Significance: Quantitative information on interactions is required to understand the complex processive mechanism.

Due to its elevated cellulolytic activity, the filamentous fungus Trichoderma harzianum (T. harzianum) has considerable potential in biomass hydrolysis application. Cellulases from Trichoderma reesei have been widely used in studies of cellulose breakdown. However, cellulases from T. harzianum are less-studied enzymes that have not been characterized biophysically and biochemically as yet. Here, we examined the effects of pH and temperature on the secondary and tertiary structures, compactness, and enzymatic activity of cellobiohydrolase Cel7A from T. harzianum (Th Cel7A) using a number of biophysical and biochemical techniques. Our results show that pH and temperature perturbations affect Th Cel7A stability by two different mechanisms. Variations in pH modify protonation of the enzyme residues, directly affecting its activity, while leading to structural destabilization only at extreme pH limits. Temperature, on the other hand, has direct influence on mobility, fold, and compactness of the enzyme, causing unfolding of Th Cel7A just above the optimum temperature limit. Finally, we demonstrated that incubation with cellobiose, the product of the reaction and a competitive inhibitor, significantly increased the thermal stability of Th Cel7A. Our studies might provide insights into understanding, at a molecular level, the interplay between structure and activity of Th Cel7A at different pH and temperature conditions.