Cerami A, Vlassara H, Brownlee M
Laboratory of Medical Biochemistry, Rockefeller University, New York, NY 10021.
Diabetes Care. 1988 Nov-Dec;11 Suppl 1:73-9.
Glucose and other reducing sugars can react with proteins and nucleic acids, without the aid of enzymes, to form stable covalent adduct. These reactions, although studied by food chemists, have recently been found to occur in vivo. This has led to studies on the accumulation of these advanced glycosylation end products (AGE) and the role it plays in the aging of long-lived proteins and nucleic acids. In contrast to the Amadori product, which is in equilibrium with glucose, AGE is irreversibly attached to the proteins. The AGE moieties are brown, fluorescent chromophores that can cross-link proteins. We have identified and characterized two specific AGE glucose-derived cross-links in proteins 2-furoyl-4(5)-(2-furanyl)-1H-imidazole (FFI) and 1-alkyl-2-formyl-3,4-diglycosylpyrrole (AFGP). By use of a radioimmunoassay for FFI identification, it has been possible to demonstrate the presence of FFI in situ in proteins that had been exposed to glucose in vitro and in vivo. Recently, we found that reducing sugars react with amino groups on DNA nucleotides in a manner analogous to the nonenzymatic glycosylation of amino groups on proteins. The AGE-DNA formed in this manner has spectral and fluorescent properties similar to those of AGE-proteins. We have observed that formation of AGE on DNA decreases the ability of the single-stranded virus f1 to transfect Escherichia coli. When the plasmid pBR322 containing ampicillin- and tetracycline-resistant genes is incubated with reducing sugars, specific mutations are observed. These mutations have been found to be caused by insertions and deletions of the DNA. Further studies are needed for measuring the amounts of AGE-DNA and proteins linked to DNA by AGE. Potential mechanisms for repair of AGE-DNA also needs to be explored further.(ABSTRACT TRUNCATED AT 250 WORDS)
葡萄糖和其他还原糖无需酶的参与，就能与蛋白质和核酸发生反应，形成稳定的共价加合物。尽管食品化学家对这些反应进行过研究，但最近发现它们也会在体内发生。这引发了对这些晚期糖基化终产物（AGE）积累情况及其在长寿蛋白质和核酸老化过程中所起作用的研究。与处于葡萄糖平衡状态的阿马多利产物不同，AGE与蛋白质的结合是不可逆的。AGE部分是棕色的荧光发色团，能够使蛋白质交联。我们已经鉴定并表征了蛋白质中两种特定的源自葡萄糖的AGE交联物，即2-呋喃甲酰基-4(5)-(2-呋喃基)-1H-咪唑（FFI）和1-烷基-2-甲酰基-3,4-二糖基吡咯（AFGP）。通过使用针对FFI鉴定的放射免疫分析法，已能够在体外和体内接触过葡萄糖的蛋白质中原位证明FFI的存在。最近，我们发现还原糖与DNA核苷酸上的氨基发生反应的方式类似于蛋白质上氨基的非酶糖基化反应。以这种方式形成的AGE-DNA具有与AGE-蛋白质相似的光谱和荧光特性。我们观察到DNA上AGE的形成会降低单链病毒f1转染大肠杆菌的能力。当将含有氨苄青霉素和四环素抗性基因的质粒pBR322与还原糖一起孵育时，会观察到特定的突变。已发现这些突变是由DNA的插入和缺失引起的。还需要进一步研究来测量AGE-DNA的量以及与DNA相连的AGE修饰的蛋白质的量。AGE-DNA的修复潜在机制也需要进一步探索。（摘要截短至250字）
