- Characterisation of the aminopeptidase from non-germinated winter rape (Brassica napus L.) seeds
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Rapeseed plays a crucial role in food and fuel industry. Since aminopeptidases take part in many physiological processes in all organisms, it is important to learn their role and characteristics in economically relevant plants. Extracts of non-germinated winter rape seeds were screened for aminopeptidase activity. Substrate specificity, the influence of pH and temperature, as well as effect of protease inhibitors and chosen metal ions on the aminopeptidase activity were determined. The approximate molecular weight estimated by NATIVE-PAGE and SDS-PAGE electrophoresis was ~60 kDa. The partially purified enzyme as well as the aminopeptidases present in crude extract cleaved preferentially Phe-pNA. The activity profiles toward several substrates were also determined. Maximum activity was observed at pH 6.5 and temperature of 40 °C for Phe-pNA as a substrate. Two visible picks in the pH profile toward Phe-pNA, together with other results (IEF) suggest the presence of more than one aminopeptidase, having similar molecular mass. Much lower activity and broad pH profiles were observed for Leu- and Ala-pNA as substrates.
- Kania, Joanna,Gillner, Danuta M.
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p. 180 - 186
(2016/04/19)
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- Purification and Some Properties of a Protease from the Sarcocarp of Musk Melon Fruit
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A protease has been purified from sarcocarp of musk melon.Cucumis melo ssp. melo var. reticulatus Naud.Earl's Favourite.The protease was mostly present in the placenta part of the fruit and next in the inside mesocarp.The molecular mass of the enzyme was estimated to be about 62 kDa on SDS-PAGE.The enzyme had a carbohydrate moiety.The optimum pH of the enzyme was 11 at 35 deg C using casein as a substrate.The enzyme was stable between pH 6 and 11.The enzyme was strongly inhibited by diisopropyl fluorophosphate, but was not inhibited by EDTA or cysteine protease inhibitors.From the digestion of Ala-Ala-Pro-X-pNA (X = Phe, Leu, Val, Ala, Gly, Lys, Glu, Pro, and diaminopropionic acid (Dap) substrates the specificity of the protease was found to be approximately broad, but the preferential cleavage sites were C-terminal sites of h)drophobic or acidic amino acid residues at P1 position.It was proved that the enzymatic properties of musk melon protease are similar to those of cucumisin .The enzvme was not inhibited by typical proteinous inhibitors such as STI or ovomucoid.Therefore, this enzyme seems to be a useful protease for the food industries. - Keywords: Cucumis melo; Cucurbitaceae; musk melon; plant protease; serine protease.
- Kaneda, Makoto,Yonezawa, Hiroo,Uchikoba, Tetsuya
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p. 2100 - 2102
(2007/10/03)
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- Thermodynamics of enzymic synthesis of solid-phase peptides
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The Gibbs free energy changes of the individual and net synthetic equilibrium of solid-phase tert-butyloxycarbonyl-Phe-Gly p-substituted anilides are calculated from the HPLC analysis data for the equilibrium concentrations. A linear free energy relationship is observed for the net synthetic equilibrium and precipitation equilibrium, suggesting that the latter provides the driving force for the chymotryptic synthesis of these insoluble peptides. This conclusion is strongly supported by a linear correlation between the synthetic yield and the square root of the product solubility.
- Ivanov, Ivailo P.,Todorov, Nikolay P.,Petkov, Dimiter D.
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p. 2307 - 2316
(2007/10/02)
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