Markwell J P, Thornber J P, Skrdla M P
Biochim Biophys Acta. 1980 Jul 8;591(2):391-9. doi: 10.1016/0005-2728(80)90170-x.
A chemical assay for P-700 was developed using 0.36 mM potassium ferricyanide as oxidant and 1.6 mM sodium ascorbate as reductant. The major difference from other chemical assays for P-700 is procedural. The method is designed to take advantage of the availability of microprocessor-linked spectrophotometers to obtain greater accuracy by minimizing the spectral changes due to irreversible oxidized antenna chlorophyll molecules. The value measured for the P-700 concentration in a sample of chloroplasts was not changed by the presence of EDTA, Mg2+ or sucrose in the assayed solution. Similarly, half of the detergents tested (Triton X-100, Nonidet P-40, digitonin, Deriphat 160, Miranol S2M-SF and Miranol M2M) did not alter the value when added to the chloroplasts. The remainder of the detergents examined caused a significant decrease or increase in the value for P-700 content. Sodium dodecyl sufate, of particular interest due to its widespread use, caused a doubling in the amount of apparent P-700. This effect may be due to this detergent and some others enabling an additional long wavelength form of chlorophyll, possibly an intermediary electron acceptor in Photosystem I, to be chemically oxidized and reduced under the assay conditions.
开发了一种用于测定P - 700的化学分析方法，使用0.36 mM铁氰化钾作为氧化剂，1.6 mM抗坏血酸钠作为还原剂。该方法与其他用于P - 700的化学分析方法的主要区别在于操作步骤。该方法旨在利用与微处理器相连的分光光度计，通过最小化由于不可逆氧化的天线叶绿素分子引起的光谱变化来获得更高的准确性。在测定溶液中存在EDTA、Mg2+或蔗糖时，叶绿体样品中测得的P - 700浓度值没有变化。同样，所测试的一半洗涤剂（Triton X - 100、Nonidet P - 40、洋地黄皂苷、Deriphat 160、Miranol S2M - SF和Miranol M2M）添加到叶绿体中时不会改变该值。其余检查的洗涤剂会导致P - 700含量值显著降低或升高。由于其广泛使用而特别受关注的十二烷基硫酸钠，使表观P - 700的量增加了一倍。这种效应可能是由于这种洗涤剂和其他一些洗涤剂能够使叶绿素的另一种长波长形式（可能是光系统I中的一种中间电子受体）在分析条件下被化学氧化和还原。
