Abstract
Summary: Complexed poly(3‐hydroxyalkanoate)s (cPHAs), one of two types of natural PHAs, occur in both prokaryotes and eukaryotes as a complex with biomacromolecules and could be involved in various physiological functions. In this study, a cPHA‐component derived from a complex with calcium polyphosphate was isolated from sugar beet (Beta vulgaris L.) and determined to be a homopolymer composed of 3‐hydroxybutyrate. MALDI MS provided the number‐average molecular weight ($\overline M _{\rm n}$ = 9 124 Da) and polydispersity index (PDI = 1.01), showing that beet cPHA has a slightly lower molecular mass than the known Escherichia coli cPHA. In addition, the structural analysis of both end groups showed that (i) 100 mol‐% of the carboxyl end is free, while about 30 mol‐% of the hydroxyl end is free and about 70 mol‐% masked and (ii) the end hydoxyl group is masked by at least six identified short‐chain alkanoic and alkanedioic acids. Based on such end‐group characteristics, the polymerization mechanism of beet cPHA is discussed.
Chemical structures of beet cPHA.
magnified imageChemical structures of beet cPHA.