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首页> 外文会议>Annual Meeting of the American Association of Cereal Chemists International >Branching pattern differences among maize amylopectins varying in starch-branching enzyme isoform activities
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Branching pattern differences among maize amylopectins varying in starch-branching enzyme isoform activities

机译：玉米支链淀粉中的分支模式差异在淀粉分支酶同种型活性中变化

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The starch-branching enzyme (SBE) isoforms contribute to establishing the branching pattern (BP) of amylopectin (AP). Previous analyses of debranched beta-limit dextrin (b-LD) suggest that the absence of SBE IIb affects BP, but the absence of SBE Ia or SBE IIa has no effect. The present objective was to describe differences in AP BP for endosperm starches differing in these SBE isoforms. Four starches represent either the full complement of SBE activities (wx), or a series of starches deficient in either SBE Ia (sbe1a wx), SBE IIa (sbe2a wx), and SBE IIb (ae wx). One starch with two missing SBE isoforms (sbe1a ae wx) was also analyzed to explore whether an effect of sbe1a might only be observed in the presence of ae. The progress of digestion of APduring beta-amylolysis and the progress of debranching of b-LD by pullulanase (PUL) or by isoamylase (IA) were analyzed. In an early stage of beta-amylolysis, different susceptibility to beta-amylase was observed for ae wx and sbe1a ae wx, and both showed more susceptibility to beta-amylase than wx, sbe1a wx, and sbe2a wx. In the final stage of beta-amylolysis, digestion of sbe1a wx and sbe2a wx starches resulted in slower reduction of degree of polymerization (DP) 4 chains to DP 2 stubs as compared towx. We ascribe these observed differences in progress of beta-amylolysis to differences in the proportion of closely associated branching points. b-LDs of the two ae-containing starches were less well debranched by either PUL or IA, consistent with major differences in BP. Differences in the progress of beta-amylolysis are consistent with the idea that loss of each isoform has an independent influence on BP.
机译：淀粉分支酶（SBE）的同种型有助于建立支链淀粉的分支模式（BP）（AP）。脱支β-极限糊精（B-LD）的前面的分析表明，不存在SBE IIB的影响BP，但由于没有SBE Ia或SBE IIA的没有效果。本目的是描述用于胚乳淀粉在这些同种型SBE在不同AP BP差异。四吨淀粉代表或者SBE活动（WX）的全面补充，或一系列淀粉在任一SBE IA（sbe1a WX），SBE IIA（sbe2a WX），和SBE IIB（AE WX）缺陷。还分析了带有两个缺失SBE同工型（sbe1a AE WX）一种淀粉，探讨是否可能只在AE的存在下观察到sbe1a的效果。 APduring的β-淀粉分解和支链淀粉酶由（PUL）或通过异淀粉酶（IA）脱支B-LD的进度的消化的进展进行分析。在的β-淀粉分解的初期阶段，观察到AE WX和sbe1a AE WX不同易感性β-淀粉酶，并均显示更易感性β-淀粉酶比WX，sbe1a WX和sbe2a WX。在的β-淀粉分解，的sbe1a WX和sbe2a WX淀粉消化的最后阶段导致减少较慢聚合度（DP）4支链DP 2存根相比towx。我们赋予中的β-淀粉分解的进步紧密相关的分支点的比例差异，这些观察到的差异。 B-LD的两个含AE-淀粉均较差由任一PUL或IA，在BP主要差别一致脱支。 β-联淀粉分解的进度差异是一致的想法，每个亚型的损失对BP独立的影响是一致的。

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