Immunological evidence for in vivo production of novel advanced glycation end-products from 1,5-anhydro-D-fructose, a glycogen metabolite

Abstract

The anhydrofructose pathway is an alternate pathway for glycogen degradation by α-1,4-glucan lyase. The sugar 1,5-anhydro-D-fructose (1,5-AF) acts as the central intermediate of this pathway, but its physiological role of in mammals is unclear. Glycation reactions forming advanced glycation end-products (AGEs) are important in the development of complications of diabetes mellitus. We hypothesized that 1,5-AF may contribute to cellular damage by forming 1,5-AF-derived AGEs (AF-AGEs) with intracellular proteins. To clarify the role of 1,5-AF in protein modification, we created a novel antibody targeting AF-AGEs. Serum albumin modified by AF-AGEs was prepared by incubating rabbit serum albumin (RSA) or bovine serum albumin (BSA) with 1,5-AF. After immunizing rabbits with AF-AGEs-RSA, affinity chromatography of anti-AF-AGE antiserum was performed on a Sepharose 4B column coupled with AF-AGEs-BSA or N-(carboxymethyl)/N-(carboxyethyl)lysine-BSA. A novel immunopurified anti-AF-AGE antibody was obtained and was characterized using a competitive enzyme-linked immunosorbent assay. Then an AF-AGEs assay was established using this immunopurified antibody. This assay was able to detect AF-AGEs in human and animal serum samples. Finally, intracellular accumulation of AF-AGEs was shown to be associated with damage to cultured hepatocytes (HepG2 cells). This is the first report about in vivo detection of AF-AGEs with a novel structural epitope.

Collagen Biosynthesis, Processing, and Maturation in Lung Ageing

“…First of all, AGEs are derived from many different precursor molecules and represent a highly heterogeneous group of compounds ( 253 , 269 ). New variants of AGEs are still being discovered ( 270 ) and it is likely that not all AGE-protein adducts and crosslinks are known in molecular detail. For the analysis of clinical samples, early detection methods took advantage of the fluorescent properties of many AGEs: Collagen from connective tissue was extracted and solubilized by collagenase digestion and fluorescence measured [≈370 nm excitation/440 nm emission ( 271 )].…”

Dissecting Sex‐Related Cognition between Alzheimer’s Disease and Diabetes: From Molecular Mechanisms to Potential Therapeutic Strategies

“…Products. Advanced glycation end products (AGEs) are produced when reducing sugars do not enzymatically react with the amino groups of proteins and then go through further reactions (including condensation, dehydration, and rearrangement) to turn into irreversibly cross-linked heterogeneous derivatives [133]. Interestingly, in 1912, AGEs were initially identified as Maillard reaction's end products [134].…”

Hypothesis: A Novel Neuroprotective Role for Glucose-6-phosphatase (G6PC3) in Brain—To Maintain Energy-Dependent Functions Including Cognitive Processes

“…When purified it had a high substrate specificity for AF, with no detectable activity with glucose, mannose, or fructose [73] indicating that this enzyme is not aldose reductase that reduces glucose to sorbitol. AF is a reactive compound, and its advanced glycation endproducts are detectable in human and animal serum; these compounds accumulate in and are associated with damage to cultured hepatocytes [74].…”