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Preparation of Free and of Specifically Protected Oligo[β‐Malic Acids] for Enzymatic Degradation Studies
Author(s) -
Krell Christoph M.,
Seebach Dieter
Publication year - 2000
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200004)2000:7<1207::aid-ejoc1207>3.0.co;2-2
Subject(s) - chemistry , degradation (telecommunications) , enzyme , malic acid , organic chemistry , malic enzyme , biochemistry , telecommunications , computer science , dehydrogenase , citric acid
The polyanionic poly[β‐( S )‐malic acids] (β‐PMA) occur in slime molds (myxomycetes), black yeasts and other fungi and are involved in DNA replication. In order to be able to study the cleavage mechanism of β‐PMA hydrolases, we have synthesized cyclic and linear oligomers of malic acid (β‐OMA) consisting of up to eight residues. To this end, fragments with three different protecting groups were prepared, with allyl ester groups on the C ‐terminus, TBDPS groups at the O ‐terminus, and benzyl ester groups at the side chains (Schemes 2, 3, 7). Selective deprotection and fragment coupling (COCl 2 /C 5 H 5 N/CH 2 Cl 2 /‐75 °C) gave dimers, tetramers, and octamers, either fully protected or specifically protected at the O ‐ or C ‐terminus or at the side chain acid groups, and also fully deprotected oligoacids (Schemes 3‐7). The new compounds were fully characterized ( R f , IR, 1 H‐ and 13 C‐NMR spectroscopy, mass spectrometry and elemental analysis or high‐resolution electrospray mass spectrometry). Enzymatic degradation experiments with the previously prepared cyclo‐tetramer, the unprotected, and the O ‐ or C ‐terminally protected samples of linear β‐OMAs show that the enzyme from Physarum polycephalum is an exo ‐hydrolase cleaving the chain from the O ‐terminus.