NATURAL POLY(L-MALIC ACID) - NMR SHOWS A POLY(3-HYDROXY ACID)-TYPE STRUCTURE

Poly(L-malic acid) was recently isolated for the first time from Physarum polycephalum, a myxomycete for which it plays the role of a coordinator during DNA replication. To determine the chain structure of this new natural polymer, its high-resolution H-1 and C-13 NMR spectra were compared with those of other poly(malic acids), namely, synthetic poly(beta-L-malic acid) and poly(alpha-L-malic acid-co-beta-L-malic acid). Both synthetic and natural poly(malic acids) as well as their mixture displayed similar H-1 and C-13 NMR spectra. In contrast, poly(alpha-L-malic acid-co-beta-L-malic acid) oligomers exhibited different NMR characteristics. These findings confirmed that natural poly(L-malic acid) belongs to the family of poly(3-hydroxy acid)-type aliphatic polyesters. It was further deduced from resonance stereosensitivity that the stereoregularity of natural poly(beta-L-malic acid) is very high.