tổng quan về phụ gia chống oxy hóa

... (tạo phức vô hại) - Loại bỏ oxy (oxy hóa ascorbic) - Phục hồi chống oxy hóa Cơ chế phục hồi chất chống oxy hóa SH + A → AH + S Xét cho chất chống oxy hóa chất béo phụ gia thực chất là: 39 + Ngăn ... gia chống oxy hóa Phụ gia chống oxy hóa loại phụ gia giúp ngăn chặn làm chậm trình oxy hóa Chúng ngăn cản trình phá hủy thực phẩm cách khử gốc tự do, oxy hóa chình nhằm kìm hãm oxy hóa Chúng ... trình oxy hóa: chất béo, vitamin, hợp chất phenolic • Tác nhân gây oxy hóa: oxy, gốc tự do, có mặt ion kim loại, enzyme oxy hóa khử  Chống oxy hóa: loại bỏ tác nhân gây oxy hóa Quá trình oxy hóa...

Ngày tải lên: 29/03/2015, 13:52

Ngày tải lên: 17/09/2013, 14:10

... D-Ala approximately 65% of that in the presence of PLP However, the addition of mm hydroxylamine or 10 mm amino-oxyacetic acid completely abolished activity, suggesting that A thaliana d-AAT is a ... deamination and decarboxylation [43,49,50] It was proposed that exogenous d-Trp is metabolized to indolepyruvate by stereospecific d-Trp AT (see above), and that this is followed by decarboxylation and ... gland [9,10], stimulates prolactin secretion in the anterior pituitary gland [11,12], modulates oxytocin and ⁄ or vasopressin synthesis in the posterior pituitary gland [13,14], and stimulates...

Ngày tải lên: 30/03/2014, 04:20

... thiết cho tăng trưởng cho trẻ mà người ta cho thể trẻ chưa tự tổng hợp được, arginin histidin (arginine histidine) XV.3 Tính chất hóa học XV.4.1 Phản ứng cháy (H2N)nCxHy(COOH)n’ + ( x + H2N-CnH2n-COOH ... natri axit glutamic (monosodium glutamat) dùng làm gia vị cho thức ăn (bột hay mì chính) Một số amino axit dùng làm nguyên liệu cho việc sản xuất tơ tổng hợp (axit ω-amino enantoic, H2N-CH2-CH2-CH2-CH2-CH2-CH2-COOH, ... tím hóa đỏ Còn loại amino axit có chứa số nhóm chức amin (−NH2) nhiều số nhóm chức axit (−COOH) gọi amino axit bazơ (như lizin), hòa tan nước tạo dung dịch có tính bazơ, làm đổi màu qùi tím hóa...

Ngày tải lên: 01/08/2014, 21:21

... tơng ứng l 0,402 v 0,335; g mái, hệ số tơng quan r tơng ứng hai giai đoạn l 0,240 v 0,210 Nh vậy, hệ số tơng quan giai đoạn 22-35 ng y tuổi lớn so với giai đoạn 22-40 ng y Những kết phù hợp với ... g mái Kết phân tích tơng quan cho thấy: có tơng quan tuyến tính thuận tăng trọng g v mức protein phần g trống, giai đoạn 22-35 ng y tuổi v 22-40 ng y tuổi hệ số tơng quan r tơng ứng l 0,402 v ... THảO LUậN tuần nuôi đầu (P>0,01) Giai đoạn 0-35 ng y tuổi, lô g trống (khẩu phần A/C) tăng trọng nhanh nhất, cao lô (khẩu phần B/E) với P< 0,01 Trong suốt thời gian thí nghiệm (0-40 ng y tuổi),...

Ngày tải lên: 29/08/2013, 08:17

Ngày tải lên: 21/12/2013, 21:15

... ester and anhydrous acetyl chloride were purchased from Alltech (Deerfield, IL), and butylated hydroxytoluene (BHT) was obtained from Spectrum Chemical MFG Corp (Gardena, CA) Anhydrous sodium sulfate ... Christie (24) Resulting FAMEs were dissolved in 10 mL of cyclohexane (0.01% BHT) for GC analysis Quantitative analysis was carried out by GC-FID using a HewlettPackard 6890 GC system with split ... light Extracts of gac fruit tissue were analyzed for carotenoid content by separation followed by quantitation using a reversed-phase HPLC system, consisting of a Waters (Milford, MA) 2690 Separation...

Ngày tải lên: 09/02/2014, 00:08

... found that Pro hydroxylation happens with high specificity; that is, only one Pro residue is hydroxylated in many conotoxins However, the physiological role of specific Pro hydroxylation in conotoxins ... modifications have been found in conotoxins, such as C-terminal amidation, hydroxylation of Pro, Val or Lys, c-carboxylation of Glu, glycosylation of Ser or Thr, bromination of Trp, sulfation of ... from the skin of the Table D-Amino acid-containing peptides from different organisms hydroxyproline; c, c-carboxylated glutamate American frog Phyllomedusa [9] Later, this was found in other toxins...

Ngày tải lên: 18/02/2014, 17:20

... enzyme–substrate complex as closely as possible, we synthesized a stable molecule [3(R)-hydroxy-2-oxo-4-phosphonoxybutyl]phosphonic acid (HOP), with the highest similarity to the natural substrate 1,3-BPGA ... complex, the hydroxy group on C3 does not interact with residues of the active site, and all molecules bearing this OH are inhibitors with respect to both substrates This hydroxy group is known ... phosphonate position in the gGAPDH–thioester complex (Fig 3B) It should also be stressed that the hydroxy group in the C2 position with the R configuration as in the substrate does not make any important...

Ngày tải lên: 20/02/2014, 02:21

... (KK) (Chất oxi hóa) +3 -2 Men giấm -2 CH3-COOH + H2O Axit axetic Nước 227 Giáo khoa hóa hữu Biên soạn: Võ Hồng Thái Đồng (II) oxit (CuO) oxi hóa rượu bậc tạo anđehit, anđehit bị oxi hóa tiếp CuO ... (kết tủa màu đỏ gạch) XII.6.2 Oxi hóa rượu bậc nhất, thu axit hữu tương ứng R-CH2OH Rượu bậc + [O] ⎯ ⎯→ Chất oxi hóa thích hợp R-COOH Axit hữu + H2O Nước Chất oxi hóa như: O2 (khơng khí); CuO; K2Cr2O7/H2SO4; ... yếu Nhóm chức axit hữu cơ, −COOH, nhóm cacboxyl, coi tập hợp gồm hai nhóm: nhóm –OH (nhóm hiđroxyl) nhóm −CO− (nhóm cacbonyl) Liên kết O H nhóm hiđroxyl tự bị phân cực Đơi điện tử góp chung O...

Ngày tải lên: 25/02/2014, 08:20

... ions are made up of DAG, two 3-hydroxyl fatty acyl moieties and (x-1) hydroxyl long chain fatty acid Those B1+ fragment ions support the conclusion that the 27-hydroxyoctacosanoic acid and eicosanoic ... molecules composed of two DAG, one of which is phosphorylated, one GalA, four 3-hydroxyl fatty acids, one (x-1) hydroxyl long chain fatty acid and one a nonpolar fatty acyl residue The most intense ... A Moreover, the sugar component of B1+ lacks hydroxyl groups suitable for attachment of these fatty acids by ester bonds The appropriate hydroxyls are located at positions of amide linked acyl...

Ngày tải lên: 07/03/2014, 15:20

... xylosoxydans ssp xylosoxydans A-6 N-acyl-D-amino acid amidohydrolase; A-6-D45919: Alcaligenes xylosoxydans ssp xylosoxydans A-6 N-acyl-D-Asparate amidohydrolase; A-6-D50061: Alcaligenes xylosoxydans ... N-acyl-D-asparate amidohydrolase (48.5% identity and 56.5% similarity) from Alicaligenes xylosoxydans ssp xylosoxydans A-6 and the D-aminoacylase from Alicaligenes faecalis DA1 (54.6% identity and 62.5% ... Purification and characterization of novel N-acylD-asparate amidohydrolase from Alcaligenes xylosoxydans subsp xylosoxydans A-6 Biosci Biotechnol Biochem 57, 1145– 1148 18 Sugie, M & Suzuki, H (1978) Purification...

Ngày tải lên: 08/03/2014, 16:20

... Oxygen reactivity of D-amino acid oxidase E Rosini et al designed to produce reactive oxygen species (ROS) in tumors ROS are potentially harmful ... addition) was taken as 100% of survival Toxicity was quantified as the fraction of surviving cells relative to the untreated cells as control Oxygen reactivity of D-amino acid oxidase 12 13 Acknowledgements ... reactive oxygen species-generating enzyme system for tumour treatment Br J Cancer 70, 1131– 1135 10 Yoshikawa T, Kokura S, Tainaka K, Naito Y & Kondo M (1995) A novel cancer therapy based on oxygen...

Ngày tải lên: 16/03/2014, 02:20

... MMFRVTSVGCFLLVIVFLNLVVLTDA; defined as the I2 superfamily O, 4-trans-hydroxyproline; F, D-phenylalanine; L, D-leucine; ^, C-terminal free acid c, c-carboxyglutamate; *, C-terminal amidation The underlined parts ... Hillyard DR & Olivera BM (1998) Conantokin-G precursor and its role in c-carboxylation by a vitamin K-dependent carboxylase from a Conus snail J Biol Chem 273, 5447–5450 Jimenez EC, Olivera BM, ... Table Amino-acid sequences of I-conotoxins with a D-amino acid near the C-terminus O, 4-trans-hydroxyproline; F, D-phenylalanine; ^, C-terminal free acid Peptide r11c is presumably synthesized with...

Ngày tải lên: 16/03/2014, 22:20

... acidic polysaccharide containing 3-deoxy-D-manno-octulosonic acid (formerly, 2-keto-3deoxy-octonic acid, Kdo), belonging to the same family of higher 3-deoxyulosonic acids to which Kdn belongs ... the spectrum were found at d67.9–80.4, i.e in the region of resonances of CH groups bound to one oxygen atom The region of resonances of the anomeric protons in the H NMR spectrum (Fig 1) contained ... d1.93 and 2.07 were observed in the region of resonances of the CH3CO– groups The presence of 3-deoxynonulosonic acid with the b-configuration of the glycosidic bond followed from two doublets of...

Ngày tải lên: 17/03/2014, 10:20

... signal of the methoxyl carbon, which was derived from CH3OH used in the transesteri®cation reaction to the methyl ester from the phytyl ester of 13C-labeled chlorophyll a of the methoxycarbonyl group ... signal of the methoxyl carbon, derived from CH3OH used in the transesteri®cation reaction to the methyl ester from the phytyl ester of 13C-labeled chlorophyll a, of the methoxycarbonyl group ... FEBS 2002 was 3.7-fold The 13C-enrichment ratio of the methoxyl carbon, which is derived from the methyl carbon of L-methionine, of the methoxycarbonyl group at C-13 was 1.8-fold The C-1 to C-5 carbons...

Ngày tải lên: 17/03/2014, 17:20

... and gel electrophoresis DAAO activity was assayed with an oxygen electrode at pH 8.5 and 25 C with 28 mM D-alanine as substrate at air oxygen saturation ([O2] ẳ 0.253 mM) [14] One DAAO unit is ... process of reoxidation of reduced DAAO with oxygen is always faster than the reductive half-reaction (see Fig for Y238S) The LineweaverBurk plots of D-alanine/ oxygen turnover show a set of slightly ... lM of the appropriate dye, as reported for the wild-type enzyme [19] The solution was purged of oxygen, and the reaction was initiated by adding 10 nM XO The course of the reaction was followed...

Ngày tải lên: 17/03/2014, 17:20

... m b t kì thu chia làm giai o n n i ti p nhau: Giai o n 1: Giai o n không tuân theo nh lu t v t c làm l nh, s trao i nhi t c a thu s n ph thu c vào trư ng nhi t ban u c a Giai o n kéo dài t lúc ... thu c vào trư ng nhi t môi trư ng l nh t o ây giai o n b n c a trình làm l nh Giai o n trao i nhi t ch y u gi a l p bên bên thu s n Giai o n 3: Là giai o n cân b ng nhi t, s trao i nhi t gi a ... i gian b o qu n, th i gian b o qu n dài s gia tăng nhanh ó s thúc y nhanh t c hư h ng s n ph m T k t qu b ng 4.1 cho th y sau r a TVKHK th p ta ã lo i nh ng ph n ch a nhi u vi khu n c a cá giai...

Ngày tải lên: 25/03/2014, 04:21

... flavoprotein oxidases (and monooxygenases) react rapidly with dioxygen (exhibiting bimolecular rate constants up to 106 m)1Æs)1) and show no saturation with O2 (i.e the Kd value for oxygen is much larger ... insights into oxygenation regio- and stereoselectivity Biochemistry 45, 3206–3218 12 Hiromoto T, Fujiwara S, Hosokawa K & Yamaguchi H (2006) Crystal structure of 3-hydroxybenzoate hydroxylase from ... shows a 100-fold lower oxygen reactivity [16] The present study represents an extension of these previous studies with the goal of enhancing the reactivity of DAAO with dioxygen It is based on...

Ngày tải lên: 28/03/2014, 23:20

... parameters were determined using d-alanine (the most frequently used DAAO substrate) at a fixed (21%) oxygen concentration In order to avoid problems arising from apoprotein formation, measurements ... 15 °C and pH 7.5 in the presence (s) or absence (d) of M urea The activity was measured using an oxygen-consumption assay under the same experimental conditions used for the fluorescence analysis ... with FAD to give the corresponding holoenzyme Activity assay DAAO activity was assayed with an oxygen electrode at 25 °C, as described previously [15], using 28 mm d-alanine as substrate One...

Ngày tải lên: 30/03/2014, 11:20