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Abstract
Purification and Characterisation of an Inhibitor of Rubber
Biosynthesis from C-serum of Heavea Brasiliensis Latex
A proteinaceous inhibitor of rubber biosynthesis
was purified from the C-serum of Hevea brasiliensis latex. The
protein inhibited the incorporation of isopentenyl diphosphate into rubber.
Purification was achieved by employing three column chromatography methods:
Sephadex G-150® gel-filtration, DEAE-Cellulose®
ion exchange chromatography and Phenyl Sepharose CL-4® hydrophobiccinteraction
chromatography. The inhibtor makes up 0.3% of the total protein in the C-serum
solids and was shown to have a molecular weight of 43 700 Da by mass spectrometry.
The protein was blocked at the N-terminal. Amino acid sequence of peptide
fragments obtained from CNBr, endoproteinase Lysine-C and trypsin digestions
showed this protein to have regions of sequence similar to patatin, a protein
that constitutes approximately 40% of the total protein present in mature
potato tubers (Solanum tuberosum). Investigations showed that, like patatin,
the inhibitor has lipolytic acyl hydrolase (LAH) activity. Based on these
observations, it is thought that the inhibitory effect is due to the destruction
by LAH of the integrity of the rubber particle membrane in which the biosynthetic
enzymes are thought to be embedded.
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