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Biomedical subjects

Neil M Rigby

Publications and source records attributed to Neil M Rigby.

4 recordsLinked to original sources
PubMed2006

Maturity and storage influence on the apple (Malus domestica) allergen Mal d 3, a nonspecific lipid transfer protein.

Consumption of apples can provoke severe allergic reactions, in susceptible individuals, due to the presence of the allergen Mal d 3, a nonspecific lipid transfer protein, found largely in the fruit skin. Levels of Mal d 3 were determined in peel as a function of apple cultivar, position of the fruit growing on the tree, apple maturity, and postharvest storage by ELISA. As the apples mature, Mal d 3 levels increased, although the rate was dependent on cultivar and tree position. During storage, levels of Mal d 3 decreased in all cultivars (cvs. Cox, Jonagored, and Gala), the rate of overall decrease being greatest under controlled atmosphere conditions. There was no correlation between Mal d 3 levels and total apple peel protein, indicating specific alterations in Mal d 3 expression. Thus pre- and postharvest treatments (i.e., storage) can modify the allergen load in apple peel, the highest levels being found in overly mature and freshly harvested fruits.

Allergens↗
PubMed2004

Mass spectrometry and structural characterization of 2S albumin isoforms from Brazil nuts (Bertholletia excelsa).

Proteomic approaches have been used to characterise the main 2S albumin isoforms from Brazil nuts (Bertholletia excelsa). Whilst most isoforms ( approximately 10 discrete protein species) exhibited molecular masses of around 12 kDa with a high amino acid sequence homology, important charge heterogeneity was found, with pIs varying between 4.6 and 6.6, with one >or=7.0. Proteomic analysis showed that these corresponded to a total of six National Center for Biotechnology Information (NCBI) accessions and that three isoforms had been purified to homogeneity corresponding to gi/384327, 112754 and 99609. The latter sequence corresponds to an isoform, previously only identified at the nucleotide sequence level, had a slightly higher molecular weight (13.4 kDa), and with noticeable differences in the primary structure. Proteins corresponding to six different NCBI accessions were identified, the heterogeneity of which had been increased by posttranslational processing. Evidence was found of cyclization of the N-terminal glutamine residue in two isoforms, together with ragged C-termini, indicative of carboxypeptidase activity within the vacuole following posttranslational processing. No evidence of glycosylation was found. Circular dichroism (CD) and Fourier transform-infrared (FT-IR) spectroscopy indicated all the studied isoforms were predominantly alpha-helical in nature, but that the Mr 13400 species was structurally distinct, with a higher proportion of alpha-helical structure.

2S Albumins, Plant↗
PubMed2002

Characterization of the emulsification properties of 2S albumins from sunflower seed.

The ability of 2S albumins from sunflower seeds to stabilize oil-in-water emulsions has been investigated, demonstrating that one of the proteins (SFA8) effectively stabilizes emulsions, while another (SF-LTP) does not stabilize emulsions. The surface tension and surface dilation viscosity of these two proteins were measured, rationalizing the emulsifying ability of SFA8 in terms of its ability to form a strongly elastic monolayer at interfaces. The secondary structure changes that occur upon adsorption of SFA8 to the oil/water interface have also been studied by fluorescence, circular dichroism (CD), and Fourier-transform infrared (FT-IR) spectroscopy. It was found that the beta-sheet content of the protein increased upon adsorption at the expense of alpha-helix and random structure. Moreover, FT-IR measurements indicate the presence of intermolecular beta-sheet formation upon adsorption. Fluorescence studies with an oil-soluble fluorescence quencher indicate that the single tryptophan residue present in SFA8 may become located in the oil-phase of the emulsion. This residue is thought to be partially buried in the native protein, and these data suggest that changes in the polypeptide region flanking this residue may play an important role in the molecular rearrangement that occur on or following adsorption to the oil/water interface.

Adsorption↗