Biodegradation of cyclic and substituted linear oligomers of poly(3-hydroxybutyrate).
Biodegradation of cyclic and substituted linear oligomers of poly(3-hydroxybutyrate).
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聚（3-羟基丁酸酯）的环状和取代的线性低聚物的生物降解。
DOI：
10.1139/m95-185
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
D. Seebach
中科院分区：
文献类型：
--
作者：
H. Brandl;B. Aeberli;R. Bachofen;I. Schwegler;H. Muller;M. H. Burger;T. Hoffmann;U. Lengweiler;D. Seebach
合成并纯化环状低聚(3-羟基丁酸酯)、低聚(3-HB)，产生含有三至七个(R)-3-羟基丁酸酯单元的低聚内酯（三内酯至七内酯）。此外，以叔丁基酯或甲酯形式获得的直链3-HB八聚体在羟基末端被不同的端基取代。羟基末端被苄氧基、三氟乙酰氧基、巴豆酰氧基(S)-3-羟基丁酰氧基或芴基甲基羰氧基(FMOC)基团取代。 P(3-HB)发夹环出现在聚合物的某些区域的表面上，尤其是层状微晶的表面上。环状 3-HB 寡聚物为这些环提供了模型系统。假设它们为解聚酶提供附着点。除(R)-三内酯外，所有测试的(R)-寡内酯均被降解。三醇酯没有降解，这表明酶攻击可能是通过刚性环系统上的空间位阻来阻止的。未取代的线性八聚体被降解。当羟基末端受到 FMOC 基团保护但不依赖于游离羟基末端基团时，可以防止生物降解；所有其他保护基团都不能防止降解。甲基或叔丁基酯基团的羧基末端的取代不影响生物降解。
Cyclic oligo(3-hydroxybutyrate), oligo(3-HB), was synthesized and purified, resulting in oligolides that contained three to seven (R)-3-hydroxybutyrate units (triolides up to heptolides). In addition, linear 3-HB octamers obtained as either tert-butyl or methyl esters were substituted with different end groups at the hydroxy end. The hydroxy terminus was replaced by either a benzyloxy, trifluoroacetoxy, crotonyloxy (S)-3-hydroxybutyryloxy, or fluorenylmethylcarbonyloxy (FMOC) group. P(3-HB) hairpin loops occurred on the surface of certain regions of the polymer, especially of lamellar crystallites. Cyclic 3-HB oligomers provide a model system for these loops. It is assumed that they provide attachment points for the depolymerizing enzymes. All of the (R)-oligolides tested were degraded except the (R)-triolide. Triolides were not degraded, suggesting that enzymatic attack was prevented presumably by steric hindrance on the rigid ring system. Unsubstituted linear octamers were degraded. Biodegradation was prevented when the hydroxy terminus was protected by the FMOC group, but was not dependent on a free hydroxy terminal group; all other protecting groups did not prevent degradation. Substitution of the carboxy end of a methyl or tert-butyl ester group did not influence biodegradation.