Radding J A, Heidler S A, Turner W W
Department of Infectious Disease Research, Lilly Research Laboratories, Eli Lilly and Co., Indianapolis, Indiana 46285, USA.
Antimicrob Agents Chemother. 1998 May;42(5):1187-94. doi: 10.1128/AAC.42.5.1187.
The echinocandins are a family of cyclic lipopeptides with potent antifungal activity. These compounds inhibit the synthesis of BETA-1,3-glucan in fungi. The new semisynthetic echinocandin LY303366 was derivatized to produce a photoactivatable cross-linking echinocandin analog with antifungal activity. This analog was radioiodinated and used as a probe in microsomal membrane preparations of Candida albicans which contain glucan synthase activity. The photoaffinity probe identified two major proteins of 40 and 18 kDa in both membrane preparations. Labeling of these proteins was specific in that it required irradiation with UV light and was effectively competed against with unlabeled echinocandin analogs. In addition, the abilities of echinocandin analogs to compete with the photoaffinity probe correlated to their relative antifungal potencies and glucan synthase inhibition. The 40-kDa protein was isolated, and partial sequences were obtained from internal peptide fragments of the protein. Analysis of the sequences of these internal peptides of the 40-kDa protein revealed that it was a new protein not previously described as being involved in glucan synthesis or the mode of action of echinocandins.
棘白菌素是一类具有强大抗真菌活性的环状脂肽。这些化合物抑制真菌中β-1,3-葡聚糖的合成。新型半合成棘白菌素LY303366经过衍生化处理，生成了一种具有抗真菌活性的可光活化交联棘白菌素类似物。该类似物经放射性碘化后，用作含有葡聚糖合酶活性的白色念珠菌微粒体膜制剂中的探针。光亲和探针在两种膜制剂中均鉴定出了40 kDa和18 kDa的两种主要蛋白质。这些蛋白质的标记具有特异性，因为它需要紫外线照射，并且能被未标记的棘白菌素类似物有效竞争。此外，棘白菌素类似物与光亲和探针竞争的能力与其相对抗真菌效力和葡聚糖合酶抑制作用相关。分离出了40 kDa的蛋白质，并从该蛋白质的内部肽片段获得了部分序列。对40 kDa蛋白质这些内部肽的序列分析表明，它是一种新蛋白质，以前未被描述为参与葡聚糖合成或棘白菌素的作用方式。
