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Title: Properties and synthesis of the ribulose 1,5 bisphosphate carboxylase large subunit binding protein of Hordeum vulgare
Author: Johnson, Richard Alan
ISNI:       0000 0001 3591 357X
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 1987
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Previous published data have demonstrated that the large subunit of RuBP carboxylase (LSU) synthesised in isolated Pisum sativum (pea) chloroplasts, is associated with a soluble, nuclear-encoded protein. This protein is termed the LSU binding protein (BP) and this observation was confirmed in the present work. The pea BP has previously been shown to consist of two subunits and work presented in this research project has confirmed this observation. Further research on the pea BP revealed that the BP subunits have different isoelectric points, partial proteolytic digestion products and that both subunits are released upon dissociation by ATP and Mg2+ ions. This dissociation is specific to ATP; ADP did not have the same effect. Analysis of soluble Hordeum vulgare (barley) and Triticum aestivum (wheat) chloroplast extracts revealed that proteins with a similar molecular mass to the pea BP cross-reacted immunogenically with antiserum raised against the pea BP. This protein was shown to bind newly- synthesised LSU in isolated barley chloroplasts. Antiserum raised against the barley BP cross-reacted monospecifically with both the barley and pea BP. The barley BP was purified to homogeneity and its physical and chemical characteristics determined. The barley BP was similar to the pea BP in that it consisted of two dissimilar subunits present in equal staining intensities. The barley BP also dissociated to its constituent subunits in the presence of ATP and Mg2+ ions. The physical properties of the barley BP differed in several aspects from those of the pea BP. The native and subunit molecular masses of the barley BP were greater than the pea BP and the isoelectric points and partial proteolytic digestion patterns also differ. The accumulation of the BP during normal leaf development was assayed by rocket immunoelectrophoresis and compared to the accumulation of RuBP carboxylase. Radiolabelling experiments in vivo were also carried out using isolated mesophyll protoplasts and these results suggest that the barley BP subunits (as in pea) are nuclear-encoded. The results presented in this research project are discussed with particular reference to the possible role of the BP in the assembly of RuBP carboxylase.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD Chemistry ; QK Botany ; QP Physiology