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Title: Purification and characterisation of putative protein allergens from the seeds of the castor oil plant Ricinus communis
Author: McGurl, Barry Francis
ISNI:       0000 0001 3624 6510
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 1986
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The identification, purification and characterisation of putative castor bean allergens has been achieved together with some studies on the synthesis of castor bean cDNA undertaken as a prerequisite to the isolation of allergen cDNA clones. At least four proteins have been identified which bind immunoglobulin E from the pooled sera of ten patients allergic to castor beans (CB pool). The apparent molecular weights of these proteins are 10,000, 34,000, 48,000 and 50.000. On the basis of their ability to elicit an IgE response these proteins are considered to be putative castor bean allergens. The 10 kDa putative allergen has been identified as the large subunit of a heterodimeric 2S storage albumin purified in the course of this study. The putative 2S allergen has been shown to be identical to a castor bean 2S albumin previously purified and sequenced by Li and coworkers (Li et al., 1977; Sharief and Li, 1982). In consequence, the putative 2S allergen has been called Li's protein. Li's protein has been shown to be a trypsin inhibitor. Li's protein may be encoded by a multigene family and is initially translated as a 32.5 kDa precursor, almost three times the mass of the mature protein (11 kDa) as determined by amino acid sequencing. IgE from the CB pool specifically binds to two components of the complex crystalloid group of storage proteins. The 34 kDa subunits of these crystalloid proteins may be the putative 34 kDa allergen. The binding of IgE from the CB pool by components of the crystalloid complex may be the result of a cross-reaction with IgE raised against the 2S allergen. The putative crystalloid allergens have been substantially purified by ion-exchange chromatography. The feasibility of using chromatofocusing to rigorously purify the putative crystalloid allergens and to separate the individual polypeptides has been investigated. The SI nuclease method was found to be preferable to the RNAse H method for the synthesis of castor bean cDNA. The 48 kDa and 50 kDa putative castor bean allergens have not been identified.
Supervisor: Not available Sponsor: Science and Engineering Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD Chemistry ; QK Botany ; QR Microbiology ; SB Plant culture