McGurl, Barry Francis (1986) Purification and characterisation of putative protein allergens from the seeds of the castor oil plant, "Ricinus communis". PhD thesis, University of Warwick.

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Abstract

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.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QD Chemistry Q Science > QK Botany Q Science > QR Microbiology S Agriculture > SB Plant culture
Library of Congress Subject Headings (LCSH):	Castor oil plant -- Genetics, Proteins -- Analysis , Crystalloids (Botany), Allergens, Castor beans -- Molecular aspects
Official Date:	November 1986
Dates:	Date Event November 1986 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Biological Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Lord, Mike (J. Mike)
Sponsors:	Science and Engineering Research Council (Great Britain)
Extent:	xxii, 241 leaves
Language:	eng

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