One-Step Synthesis of Biotinyl Photoprobes from Unprotected Carbohydrates
摘要:
A simple and versatile approach for the preparation of carbohydrate photoprobes has been developed. By a single-step reaction at 37 degrees C, a biotinylated carbene-generating unit was introduced to the reducing end of unprotected carbohydrates. Micromole quantities of N-acetyllactosamine, Lewis X trisaccharide, and sialyl Lewis X tetrasaccharide were easily converted to their biotinylated photoreactive analogues, which enabled the nonradioisotopic chemiluminescent detection of the photolabeled products. Thus, a sequence of lectin photoaffinity labeling, from the probe synthesis to the detection of labeled protein, was readily accomplished within one week. Our strategy may be applicable to any aldehyde-bearing ligand.
Phenyldiazirine compounds and photoaffinity labeling reagent
申请人:Hatanaka Yasumaru
公开号:US06903223B1
公开(公告)日:2005-06-07
This invention offers a photoreactive labeling reagent consisting of a novel biotinylated phenyldiazirine compound; a photoaffinity labeling reagent consisting of a saccharide-linked biotinylated phenyldiazirine compound where a saccharide compound is introduced into the novel compound; and a novel diazirine compound for such a reagent. The invention covers a biotinylated phenyldiazirine compound of the following formula (II); a phenyldiazirine compound which is an intermediate for synthesizing the above; a saccharide-linked biotinylated phenyldiazirine compound derived from the compound of the formula (II) and a saccharide compound and a method for manufacturing the same; a photoreactive labeling reagent containing the compound of the formula (II); a photoaffinity labeling reagent containing the saccharide-linked biotinylated phenyldiazirine compound; and a method for labeling a saccharide receptor using the reagent.
A biotin-conjugated photoactivatable phenylaminodiazirine derivative of 2,3-didehydro-2-deoxy-N-acetylneuraminic acid (DANA) was synthesized to identify sialidase. The free carboxylic group and N-acetyl substituent of sialic acid, which are important for recognition and enzymatic activity of sialidase, were conserved by the photolabeling compound as confirmed using analytical methods. The synthesized compound and DANA competitively inhibited starfish sialidase with a Ki value of 7.6 μM and 4.6 μM, respectively. Photo incorporation of the labeling compound to sialidase increased with irradiation time; 90% photo incorporation was achieved with more than 10-min irradiation, and labeling was completely inhibited by the addition of a competitive inhibitor. Starfish sialidase purified using high-performance gel filtration chromatography was subjected to photoaffinity labeling. A 50-kDa band was revealed to contain the sialidase active site by the photolabeling compound, and labeling was completely hindered in presence of the competitive inhibitor. Labeling specificity was ensured by the addition of the heat-deactivated standard protein chymotrypsinogen A to the reaction mixture.
合成了一种 2,3-二脱氢-2-脱氧-N-乙酰神经氨酸(DANA)的生物素共轭可光激活的苯氨基二氮氨酸衍生物,用于识别硅氨酸酶。光标记化合物保留了硅氨酸的游离羧基和 N-乙酰取代基,这两个基团对硅氨酸酶的识别和酶活性非常重要,这一点已通过分析方法得到证实。合成的化合物和 DANA 能竞争性地抑制海星的硅糖苷酶,其 Ki 值分别为 7.6 μM和 4.6 μM。标记化合物与硅糖苷酶的光结合随辐照时间的延长而增加;超过 10 分钟的辐照可使光结合率达到 90%,加入竞争性抑制剂可完全抑制标记。用高效凝胶过滤色谱法纯化的海星硅糖苷酶进行了光亲和标记。光标记化合物揭示出一条 50 kDa 的条带含有硅糖苷酶的活性位点,在竞争性抑制剂存在的情况下,标记完全受阻。在反应混合物中加入热失活的标准蛋白糜蛋白酶原 A 可确保标记的特异性。
Detection of 210 kDa receptor protein for a leaf-movement factor by using novel photoaffinity probes
Circadian rhythmic plant leaf-movement, called nyctinasty, is controlled by a time-course change in the internal concentration of the leaf-movement factor in the plant body. We revealed that specific binding proteins (210 and 180 kDa) for the leaf-movement factor, potassium lespedezate (1), are contained in the plasma membrane of the plant motor cell by using novel synthetic photoaffinity probes. These proteins are localized on the motor cell in the plant body, and would be potential receptors for the leaf-movement factor to control the leaf-movement. Our study is a rare successful result of the detection of membrane receptors by using a synthetic photoaffinity probe designed on a biologically active natural product. And these results also advance a guideline for probe design towards successful photoaffinity labeling. (c) 2005 Elsevier Ltd. All rights reserved.
The effect of structural differences in the reducing terminus of sugars on the binding affinity of carbohydrates and proteins analyzed using photoaffinity labeling
Because carbohydrates and proteins bind with such low affinity, the nature of their interactions is not clear. Photoaffinity labeling with diazirin groups is useful for elucidating the roles of carbohydrates in these binding processes. However, when carbohydrate probes are synthesized according to this conventional method, the reducing terminus of the sugar is opened to provide an acyclic structure. Because greater elucidation of carbohydrate-protein interactions requires a closed-ring carbohydrate in addition to the photoreactive group, we synthesized new molecular tools. The carbohydrate ligands were synthesized in three steps (glycosylation with allyl alcohol, deprotection, and ozonolysis). Specific binding proteins for carbohydrate ligands were obtained by photoaffinity labeling. Closed ring-type carbohydrate ligands, in which the reducing sugar is closed, bound to lectins more strongly than open ring-type sugars. Carbohydrate to protein binding was observed using AFM. (C) 2010 Elsevier Ltd. All rights reserved.