Poly(L-malic acid) was recently isolated for the first time from Physa
rum polycephalum, a myxomycete for which it plays the role of a coordi
nator during DNA replication. To determine the chain structure of this
new natural polymer, its high-resolution H-1 and C-13 NMR spectra wer
e compared with those of other poly(malic acids), namely, synthetic po
ly(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 mixtu
re 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 ac
id) belongs to the family of poly(3-hydroxy acid)-type aliphatic polye
sters. It was further deduced from resonance stereosensitivity that th
e stereoregularity of natural poly(beta-L-malic acid) is very high.