摘要 :
Olive tree (Olea europaea) pollen is a main cause of allergy in Mediterranean areas and North America. A novel allergen, Ole e 11, has been detected by proteomic techniques. Protein bands binding IgE from allergic sera were excise...
展开
Olive tree (Olea europaea) pollen is a main cause of allergy in Mediterranean areas and North America. A novel allergen, Ole e 11, has been detected by proteomic techniques. Protein bands binding IgE from allergic sera were excised from a 2D electrophoresis gel and analysed by Edman degradation and MALDI-TOF MS. Four peptides were sequenced and used for designing primers to clone the cDNA codifying the protein. Ole e 11 consists of a 342 amino acid length polypeptide with a molecular mass of 37.4 kDa and a pI of 7.8. The allergen was identified as a pectin methylesterase and showed low identity with other members of this family from foods such as those from carrot (23%), orange (25%) and tomato (24%), and higher identity with those from Arabidopsis thaliana (57%) and Salsola kali (54%) pollen. The protein was overproduced in Pichia pastoris, purified, and characterized as an active enzyme. CD analysis rendered 3%l-helix, 50%o-sheet and 27%o-turns for its secondary structure, which is in agreement with other pectin methylesterase structures. The recombinant protein was demonstrated to be immunologically equivalent to the natural form by immunoblotting, indirect ELISA and inhibition experiments, using polyclonal antiserum and sera from olive pollen allergic patients. The prevalence fluctuated between 55.9% and 75.6% in three different allergic populations. The availability of this new olive pollen allergen could improve the component-resolved diagnosis. Its allergenic relevance is stepped up by the biotechnological use of these enzymes to improve organoleptic properties in processing foods and further confirms the need to include it in an accurate diagnosis.
收起
摘要 :
Olive tree (Olea europaea) pollen is a main cause of allergy in Mediterranean areas and North America. A novel allergen, Ole e 11, has been detected by proteomic techniques. Protein bands binding IgE from allergic sera were excise...
展开
Olive tree (Olea europaea) pollen is a main cause of allergy in Mediterranean areas and North America. A novel allergen, Ole e 11, has been detected by proteomic techniques. Protein bands binding IgE from allergic sera were excised from a 2D electrophoresis gel and analysed by Edman degradation and MALDI-TOF MS. Four peptides were sequenced and used for designing primers to clone the cDNA codifying the protein. Ole e 11 consists of a 342 amino acid length polypeptide with a molecular mass of 37.4 kDa and a pI of 7.8. The allergen was identified as a pectin methylesterase and showed low identity with other members of this family from foods such as those from carrot (23%), orange (25%) and tomato (24%), and higher identity with those from Arabidopsis thaliana (57%) and Salsola kali (54%) pollen. The protein was overproduced in Pichia pastoris, purified, and characterized as an active enzyme. CD analysis rendered 3%l-helix, 50%o-sheet and 27%o-turns for its secondary structure, which is in agreement with other pectin methylesterase structures. The recombinant protein was demonstrated to be immunologically equivalent to the natural form by immunoblotting, indirect ELISA and inhibition experiments, using polyclonal antiserum and sera from olive pollen allergic patients. The prevalence fluctuated between 55.9% and 75.6% in three different allergic populations. The availability of this new olive pollen allergen could improve the component-resolved diagnosis. Its allergenic relevance is stepped up by the biotechnological use of these enzymes to improve organoleptic properties in processing foods and further confirms the need to include it in an accurate diagnosis.
收起
摘要 :
Intact and crushed jelly fig (Ficus awkeotsang Makino) achenes were extracted for various periods of time, and the changes in pectinesterase (PE) activities were determined. The activity of crude PE solution from crushed achenes i...
展开
Intact and crushed jelly fig (Ficus awkeotsang Makino) achenes were extracted for various periods of time, and the changes in pectinesterase (PE) activities were determined. The activity of crude PE solution from crushed achenes increased gradually, reaching a maximum (12 U/mL) at approximately 12 h, while the PE from crushed achenes was maintained at about 0.2 to 0.3 U/mL throughout the extraction.
收起
摘要 :
Strawberry samples of two varieties (Camarosa and Elsanta) were dehydrated using different osmotic solutions (60% glucose, fructose, sucrose and raftilose) and subsequently frozen by rapid and high-pressure shift freezing (HPSF). ...
展开
Strawberry samples of two varieties (Camarosa and Elsanta) were dehydrated using different osmotic solutions (60% glucose, fructose, sucrose and raftilose) and subsequently frozen by rapid and high-pressure shift freezing (HPSF). The effect of pectinmethylesterase (PME) and calcium (Ca) added to the osmotic solutions on several compositional parameters and the textural/structural quality of dehydrated and osmodehydrofrozen-then-thawed samples was studied. Due to the presence of PME and Ca in the osmotic solutions, weight reduction upon dehydration was slightly decreased, which was correlated to a small positive effect on the net uptake of sugars and depression of the initial freezing point. Except for the Camarosa samples treated with sucrose, PME and Ca in osmotic sugar solutions positively affected the relative hardness of dehydrated fruits, which was ascribed to the effect of PME and Ca on the cell wall strength of the tissue. No cell wall damage and tissue particle alterations were observed upon dehydration. The effect of osmotic dehydration (OD) using different sugar solutions without PME and Ca on the texture and structure of frozen-then-thawed samples was limited and sometimes negative. The added PME and Ca however positively influenced the volume and shape of the thawed samples, which could be related to slightly higher relative hardness values and, for the Elsanta strawberry fruits, also to the reduced (up to 81%) drip loss upon thawing. Upon freezing the dehydrated fruits, no cell wall disruption was observed. Tissue distortion caused by freezing and indicated by a decrease in particle size, convexity and roundness, was compensated by the use of PME and Ca during OD.
收起
摘要 :
These experiments focused on processing low sugar fig jam having marketability by selected substitute for extracted and purified pectinesterase (PE), colorant for colour improvement, food additive to make texture better, and stabi...
展开
These experiments focused on processing low sugar fig jam having marketability by selected substitute for extracted and purified pectinesterase (PE), colorant for colour improvement, food additive to make texture better, and stabilizer for stable storage. Cherry tomato pulp as PE substitute to hydrolyze pectin substance in fig pulp into low-methoxyl pectin was most effective among used vegetables and fruits pulp. Carmacid-R among natural colorants for imprving color, addition of 20% starch syrup as sugar substitute for texture and addition of MULTIPHOSE~(TM) for red color change control at cold storage were effective. The low sugar fig jam processed by using the above selected materials showed higher score than others (typical jam and orange PE low sugar fig jam) for color in sensory evaluation and did no significant difference in taste, odor, texture and overall acceptability.
收起
摘要 :
A thermally tolerant form of pectin methylesterase (TT-PME) has been purified from a commercially available Valencia fresh frozen orange juice by gel filtration, heparin, and concanavalin A chromatography. TT-PME represented 8.3% ...
展开
A thermally tolerant form of pectin methylesterase (TT-PME) has been purified from a commercially available Valencia fresh frozen orange juice by gel filtration, heparin, and concanavalin A chromatography. TT-PME represented 8.3% of total PME activity in the solubilized dialysis precipitate. This TT-PME retained 83.3 +/- 1.1% relative activity after a 2 min incubation in an 80 degrees C water bath and 49.2 +/- 4.1% relative activity after a 60 s incubation in a 95 degrees C water bath. It also retained 3.3 +/- 0.6% and 8.3 +/- 1.5% relative activity at pH 3.5 and 4.5, respectively. It had a native molecular mass of 40.1 kDa (gel filtration chromatography) and a denatured M(r) of 42.7 +/- 0.1. Binding to concanavalin A and treatment with PNGase F suggests it is an N-linked glycoprotein. After extended deglycosylation with PNGase F, polypeptide bands at M(r) 41.7 +/- 0.6 (n = 4) and 40.1 +/- 0.4 (n = 4) were observed.
收起
摘要 :
Pectinesterase inhibitor(PEI) of ripened kiwi fruit(Actinidia chinensis) was separated with affinity chromatography using CNBr-activated Sepharose 4B being covalently bound by orange pectinesterse(PE). The affinity resin strongly ...
展开
Pectinesterase inhibitor(PEI) of ripened kiwi fruit(Actinidia chinensis) was separated with affinity chromatography using CNBr-activated Sepharose 4B being covalently bound by orange pectinesterse(PE). The affinity resin strongly and selectively bound PEI, which could be eluted in high yield as a single peak by pH 9.5 without loss of inhibitory activity. The separated PEI had maintained almost inhibitory activity at -25 deg C and 5 deg C during 30 days but lost it at room temperature in 4 weeks. The PEI possessed a molecular weight of 16.6 KDa, as estimated by 12.5 percent SDS-PAGE. PEI had optimum pH of 7.5, optimum temperature of below 10 deg C and stability up to 70 deg C. Also, optimum inhibitory activity for PEI was obtained in 0.2 M NaCl of substrate solutions. The kind of inhibition on tomato pectinesterase was found to be noncompetitive, using citrus pectin as substrate. Fresh orange juice added with crude PEI extracts maintained almost the same cloud stability as pasteurized juice. In case of apple juice, the addition of crude PEI extracts to apple juice had decrease of L-ascorbic acid with nearly no effect on cloud loss.
收起
摘要 :
Pectinesterase inhibitor (PEI) extract prepared from intact jelly fig (Ficus awkeotsang Makino) achenes was separated by membrane (MWCO 3 and 10 kDa) and fractionated by a Sepharose G-50 gel permeation chromatography. Results from...
展开
Pectinesterase inhibitor (PEI) extract prepared from intact jelly fig (Ficus awkeotsang Makino) achenes was separated by membrane (MWCO 3 and 10 kDa) and fractionated by a Sepharose G-50 gel permeation chromatography. Results from Sepharose G-50 gel permeation chromatography and concanavalin A Sepharose chromatography revealed PEI as polypeptides with molecular weights ranging from 3.5 to 4.5 kDa. Incubation of a PE (1 unit/mL)-PEI (2 mg/mL) mixture for 1 min decreased the PE activity by similar to50%. On the basis of the results of Lineweaver-Burk double-reciprocal plots, Michaelis constant (K-m) and V-max values for jelly fig achenes PE (pH 6.0, 30 degreesC) were 0.78 mM -OCH3 and 1.09 muequiv of -COOH/min, respectively. In addition, PEI competitively inhibited both citrus and jelly fig achenes PEs.
收起
摘要 :
The contribution of several high pressure (HP) processing related factors (pressure level, 300-400 MPa; pressure cycle, 1-3, and pressure-hold time, 30-120 min) on the inactivation of pectin methyl esterase (PME) in single strengt...
展开
The contribution of several high pressure (HP) processing related factors (pressure level, 300-400 MPa; pressure cycle, 1-3, and pressure-hold time, 30-120 min) on the inactivation of pectin methyl esterase (PME) in single strength (pH 3.7 and 11.4 degreesBrix) and concentrated (pH 3.5 and 42 degreesBrix) orange juice was evaluated. A response surface methodology was employed to model the combined effects of factors on the enzyme inactivation. The main effects were described by linear or quadratic functions. For both single strength and concentrated orange juices, the effects of all three main factors and some interactions (pressure level, cycle and holding time) were statistically significant (p < 0.05). The dual nature of pressure inactivation of PME (with an instantaneous inactivation due to a pressure pulse, instantaneous pressure kill, and first order rate of inactivation during the pressure hold, yielding D and z values) reported in earlier studies was confirmed. Combination models were developed to predict the residual enzyme activity as influenced by the pressure level, number of pressure cycles and pressure hold time.
收起
摘要 :
During Arabidopsis seed development large quantities of mucilage, composed of pectins, are deposited into the apoplast underneath the outer wall of the seed coat. Upon imbibition of mature seeds, the stored mucilage expands throug...
展开
During Arabidopsis seed development large quantities of mucilage, composed of pectins, are deposited into the apoplast underneath the outer wall of the seed coat. Upon imbibition of mature seeds, the stored mucilage expands through hydration and breaks the outer cell wall that encapsulates the whole seed. Mutant seeds carrying loss-of-function alleles of AtSBT1.7 that encodes one of 56 Arabidopsis thaliana subtilisin-like serine proteases (subtilases) do not release mucilage upon hydration. Microscopic analysis of the mutant seed coat revealed no visible structural differences compared with wild-type seeds. Weakening of the outer primary wall using cation chelators triggered mucilage release from the seed coats of mutants. However, in contrast to mature wild-type seeds, the mutant's outer cell walls did not rupture at the radial walls of the seed coat epidermal cells, but instead opened at the chalazal end of the seed, and were released in one piece. In atsbt1.7, the total rhamnose and galacturonic acid contents, representing the backbone of mucilage, remained unchanged compared with wild-type seeds. Thus, extrusion and solubility, but not the initial deposition of mucilage, are affected in atsbt1.7 mutants. AtSBT1.7 is localized in the developing seed coat, indicating a role in testa development or maturation. The altered mode of rupture of the outer seed coat wall and mucilage release indicate that AtSBT1.7 triggers the accumulation, and/or activation, of cell wall modifying enzymes necessary either for the loosening of the outer primary cell wall, or to facilitate swelling of the mucilage, as indicated by elevated pectin methylesterase activity in developing atsbt1.7 mutant seeds.
收起
原文获取