• 2018-07
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  • br Materials and methods br Results and discussion


    Materials and methods
    Results and discussion
    Conclusion The glycyl endopeptidase from papaya latex was partitioned using aqueous two-phase (10%PEG 6000–10% (NH4)2SO4) in combination with ammonium sulphate precipitation (40–60% saturation). The partially purified glycyl endopeptidase showed the potential in production of antioxidative gelatin hydrolysates. The enzyme fraction contained lower odorous compounds in papaya latex. The gelatin hydrolysate produced using the selected fraction had negligible odorous compounds. This could increase the exploitation of papaya latex for production of antioxidative gelatin hydrolysate.
    Introduction Endopeptidases (EPs) are proteases that degrade proteins by hydrolyzing internal peptide bonds. EPs are one of the best-characterized classes of cell death–related proteins in plants. These enzymes play important roles in organ senescence and programmed cell death (Schaller, 2004). EPs are classified based on the amino Mirin reviews residues or metals required for their respective cleavage reactions, and include cysteine, serine, aspartic acid, and metalloproteases. An activity gel assay is defined as an electrophoresis technique that identifies the proteolytic activity of proteins under non-denaturing conditions. These assays allow for the identification of an enzyme of interest in a complex mixture of proteases, and an estimation of its molecular weight. This method was originally applied to detect urokinase activity using a gelatin substrate slab gel (Heussen and Dowdle, 1980). Since then, activity gel assays with gelatin have been applied to detect other plant EPs (Stephenson, Rubinstein, 1998, Jiang et al, 1999). The advantage of using activity gel assays is the superior detection limit over other methods such as enzyme-linked immunosorbent assays and Western blots (Kleiner and Stetlerstevenson, 1994). Some major factors known to affect EP activity gel assays include sample extraction methods and heat treatments prior to electrophoresis, SDS–polyacrylamide gel concentration, co-polymerized gelatin concentration in the gel, incubation temperature, and pH after electrophoresis. Roses are highly economic important; they are within the top five ornamental plants worldwide in terms of economic impact. Rose has been established as the model plant for studies on the morphological development and physiological metabolism of petals (Debener and Linde, 2009). Several studies showed that senescence of roses was closely related with EP activity, which rises quickly in petals in conjunction with a drop in protein content (Liu et al, 2005, Zhao et al, 2005). Tripathi et al. (2009) also found that RbCP1, a cysteine protease, controls protein degradation during petal abscission in rose (Rosa bourboniana). It is difficult to determine EP activity by an activity gel assay because of interfering factors in rose petals such as salts and pigments. In order to understand the role of EPs in rose abscission and senescence, it will be important to optimize activity assays for these enzymes.
    Materials and methods
    Introduction Gluten proteins have become a very important field of research within food science, due to increasing gluten intolerance including allergy issues and public concern towards gluten. Approximately 1% of the world’s population suffers with celiac disease (CD) which is an autoimmune disease caused by gluten [1], [2]. Thus, there is growing focus in Denmark and world-wide on gluten free foods and beverages both for gluten intolerant and for the general public (normal people).Gluten is a common protein found in all cereals of the triticeae within the grass-family where barley, wheat, rye and oats are the main industrially relevant crops [3]. These cereals contain a network of large protein molecules surrounded by starch granules and other components. When the water-soluble proteins such as albumins and globulins along with starch are washed out, the remaining water insoluble protein fractions such as the prolamin and glutenin remains and is typically called gluten [3]. Gluten is thus a prolamin and glutenin matrix present in cereals and the prolamin part e.g. gliadin in wheat; hordein in barley; secalin in rye; avenin in oat [4], can cause a deadly allergic reaction in gluten intolerant people − termed celiac disease. Oat gluten is the subject of some controversy [5], but is generally considered non-allergenic.