000			01755nam a2200241Ia 4500
008			220216s9999 xx 000 0 und d
100			_aTanaka Y
245		0	_aInitiation of rubber biosynthesis in Hevea brasiliensis: characterization of initiating species by structural analysis
260			_bPhytochemistry _c1996
300			_a1501-1505
500			_aSource Year: 1996
520			_aTo determine the structure of the initiating species for rubber formation, the structure of the terminal group of rubber (isolated from 1-month-old seedlings of H. brasiliensis) was determined using 13C NMR and 1H NMR spectroscopy. The presence of trans-isoprene units in a trans-trans linkage was confirmed. The number of trans-isoprene units was estimated to be about 2. Two methyl-proton signals in the trans-trans sequence were detected by 1H NMR spectroscopy. This spectral evidence showed that the trans-isoprene units were in the trans-trans-cis sequence at the initiating terminal. However, the expected methyl- and olefinic-carbon signals and methyl-proton signal of the dimethylallyl group were not detected in natural rubber from either regularly tapped trees or from seedlings. Thus, the direct initiating species of rubber formation is either a C15 allylic diphosphate consisting of two trans-isoprene units as in the case of farnesly diphosphate (FDP), but which is modified at the dimethylallyl group, or it is FDP, the dimethylallyl group of which is modified after polymerization.
650			_aHevea brasiliensis
650			_aRubber biosynthesis
700			_aAik-Hwee E
700			_aKawahara S
700			_aNishiyama N
700			_aOhya N
700			_aTangpakdee J
700			_aWititsuwannakul
856			_uHOA
942			_cJS
999			_c61409 _d61409