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Properties of the System for the Mixed Function Oxidation of Kaurene and Kaurene Derivatives in Microsomes of the Immature Seed of Marah macrocarpus

机译:大果玛拉未成熟种子微粒体中考林烯和考林烯衍生物的混合功能氧化体系的性质

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摘要

The rates of oxidation of ent-kaur-16-ene to ent-kaur-16-en-19-ol, ent-kaur-16-en-19-al, ent-kaur-16-en-19-oic acid, and ent-kaur-16-en-7α-ol-19-oic acid are maximal in microsomes prepared from the endosperm of immature Marah macrocarpus seeds in which the cotyledons are approximately one-half the overall length of the seed. The supernatant fraction remaining from the preparation of the microsomes contains factors which stimulate the rates of oxidation catalyzed by the microsomes. Added TPNH is more effective than added DPNH in meeting the requirement for reduced pyridine nucleotide. A mixture of DPNH, ATP, and TPN+ is much more effective than DPNH alone. Experiments with 2,4-dinitrophenol as a selective inhibitor indicate that the ATP-stimulated synthesis of TPNH which occurs in these microsomes in the presence of this mixture of coenzymes provide TPNH for use in the mixed function oxidations. Relatively low concentrations of DPNH and TPNH together are much more effective than either alone at equivalent concentration. This is consistent with the involvement of two pathways of electron transfer associated with the mixed function oxidations, one of which preferentially utilizes TPNH and the other favoring DPNH. FAD added to microsomes at an optimal concentration of about 10 μm in the presence of TPNH stimulates the rate of the oxidations; higher concentrations are inhibitory. FMN by itself does not produce this stimulation. However, FMN and FAD added together at low concentrations (0.5 μm each) have approximately the same effectiveness as FAD alone at 10 μm. This suggests a role for both flavin nucleotides in the normal electron transfer pathways associated with these oxidations. Some of the stimulatory properties of the supernatant fraction may be accounted for by its content of reduced pyridine nucleotides, FAD, and FMN; the concentrations of FAD and FMN were determined to be 1.1 μm and 0.4 μm, respectively. However, the effects of the supernatant fraction are not completely explained by its content of these coenzymes since other experiments indicate the presence of a heat-labile, nondialyzable stimulatory factor(s) in the supernatant fraction in addition to heat-stable, dialyzable fractors.
机译:ent-kaur-16-ene氧化为ent-kaur-16-en-19-ol,ent-kaur-16-en-19-al,ent-kaur-16-en-19-oic酸的氧化速率,在未成熟的玛拉大果种子的胚乳中制备的微粒体中,ental和kaur-16-en-7α-ol-19-oic酸最大,其中子叶大约是种子总长度的一半。微粒体制备中剩余的上清液级分包含刺激微粒体催化的氧化速率的因子。在满足减少吡啶核苷酸的要求上,添加的TPNH比添加的DPNH更有效。 DPNH,ATP和TPN + 的混合物比单独的DPNH更有效。用2,4-二硝基苯酚作为选择性抑制剂的实验表明,在这些辅酶混合物存在下,在这些微粒体中ATP刺激的TPNH合成提供了用于混合功能氧化的TPNH。相对较低的浓度的DPNH和TPNH一起在等效浓度下要比单独使用的有效得多。这与涉及混合功能氧化的两个电子转移途径有关,其中一个优先利用TPNH,另一个优先利用DPNH。在TPNH的存在下,以约10μm的最佳浓度添加到微粒体中的FAD刺激了氧化速率。较高的浓度具有抑制作用。 FMN本身不会产生这种刺激。但是,以低浓度(各为0.5μm)一起添加的FMN和FAD与仅10μm的FAD具有近似相同的功效。这暗示了两个黄素核苷酸在与这些氧化有关的正常电子传递途径中的作用。上清液级分的某些刺激特性可能是由于其还原的吡啶核苷酸,FAD和FMN的含量所致。 FAD和FMN的浓度分别确定为1.1μm和0.4μm。然而,上清液级分的作用不能完全通过其这些辅酶的含量来解释,因为其他实验表明,除了热稳定的,可透析的分数外,上清液级分中还存在热不稳定的,不可透析的刺激因子。

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