Paramagnetic species in cataractous human lenses
Paramagnetic species in cataractous human lenses
复制标题
白内障人类晶状体中的顺磁性物质
作者：
J. Weiter;E. Finch
KURZEL等人1研究了正常人和白内障患者晶状体在77 K时的低温磷光发射。将他们的透镜数据与冷冻乙醇-水玻璃中色氨酸的数据进行比较后，他们得出结论，透镜的磷光是由透镜蛋白的色氨酸残基引起的。这是基于他们在透镜中发现的磷光λ（max）、磷光激发和磷光量子产率与色氨酸一致，并且与苯丙氨酸和酪氨酸的那些显著不同。在这里，我们提出的电子自旋共振（ESR）研究的结果，其特征的顺磁三重态的正常和白内障的人的晶状体，并提供证据，它源于色氨酸部分，而不是酪氨酸或苯丙氨酸。这补充了先前的观察，色氨酸是白内障人类晶状体中的主要物质，引起磷光发射。此外，我们发现透镜激发的三重态（磷光）色氨酸与自由基的产生有关;我们认为这种自由基可能是紫外线照射和导致白内障形成的透镜光损伤之间缺失的环节3，4。
KURZEL et al.1 studied the low temperature phosphorescence emission from normal and cataractous human lenses at 77 K. After comparing their lens data with those obtained from tryptophan in a frozen ethanol–water glass, they concluded that the phosphorescence of the lens is caused by the tryptophan residues of lens proteins. This was based on their finding in the lens a phosphorescence λ(max), phosophorescence excitation and phosphorescence quantum yield consistent with tryptophan and differing significantly from those of phenylalanine and tyrosine. Here we present the results of an electron spin resonance (ESR) study which characterises the paramagnetic triplet state of normal and cataractous human lenses and provides proof that it stems from the tryptophan moiety and not tyrosine or phenylalanine. This supplements previous observations that tryptophan is the dominant species in cataractous human lenses, giving rise to phosphorescent emission. In addition, we have discovered that the lens excited triplet (phosphorescent) tryptophan is associated with the production of a free radical; we believe that this free radical may be the missing link between ultraviolet irradiation and lens photodamage leading to cataract formation3,4.