A Mammalian Protein Homologous to Fructosamine-3-Kinase Is a Ketosamine-3-Kinase Acting on Psicosamines and Ribulosamines but not on Fructosamines

Abstract

Fructosamine-3-kinase (FN3K) is an enzyme that appears to be responsible for the removal of fructosamines from proteins. In this study, we report the sequence of human and mouse cDNAs encoding proteins sharing 65% sequence identity with FN3K. The genes encoding FN3K and FN3K-related protein (FN3K-RP) are present next to each other on human chromosome 17q25, and they both have a similar 6-exon structure. Northern blots of mouse tissues RNAs indicate a high level of expression of both genes in bone marrow, brain, kidneys, and spleen. Human FN3K-RP was transfected in human embryonic kidney (HEK) cells, and the expressed protein was partially purified by chromatography on Blue Sepharose. Unlike FN3K, FN3K-RP did not phosphorylate fructoselysine, 1-deoxy-1-morpholino-fructose, or lysozyme glycated with glucose. In a more systematic screening for potential substrates for FN3K-RP, we found, however, that both enzymes phosphorylated ketosamines with a D-configuration in C3 (psicoselysine, 1-deoxy-1-morpholino-psicose, 1-deoxy-1-morpholino-ribulose, lysozyme glycated with allose-the C3 epimer of glucose, or with ribose). Tandem mass spectrometry and nuclear magnetic resonance analysis of the product of phosphorylation of 1-deoxy-1-morpholino-psicose by FN3K-RP indicated that this enzyme phosphorylates the third carbon of the sugar moiety. These results indicate that FN3K-RP is a ketosamine-3-kinase (ketosamine-3-kinase 2). This enzyme presumably plays a role in freeing proteins from ribulosamines or psicosamines, which might arise in a several step process, from the reaction of amines with glucose and/or glycolytic intermediates. This role is shared by fructosamine-3-kinase (ketosamine-3-kinase 1), which has, in addition, the unique capacity to phosphorylate fructosamines.

Possible role of fructosamine 3-kinase genotyping for the management of diabetic patients

“…As expected, FN3K is more active in tissues containing proteins with long (half-)lives, such as erythrocytes, lens and brain [19]. Remarkably, FN3K activity is elevated in erythrocytes from rat, mouse and man, in whom the intracellular concentration of glucose is close to that of plasma.…”

“…Both FN3K and FN3K-RP phosphorylate psicosamines and ribulosamines, but only the former act on fructosamines [19]. As expected, FN3K is more active in tissues containing proteins with long (half-)lives, such as erythrocytes, lens and brain [19].…”

“…FN3K gene may have arisen by an event of duplication of an ancestral gene, FN3K-related protein (FN3K-RP). The gene encoding FN3K-RP is located next to the one encoding FN3K, and share a 65% sequence homology with FN3K and an identical genome organization [19,20]. Two distinct, but related genes, encoding orthologs of FN3K and FN3K-RP are present in mammals and chicken genomes, whereas there is only one FN3K/ FN3K-RP homolog in the genomes of fishes and urochordates [20], suggesting that the gene duplication event occurred during fish radiation.…”

Advancing the Development of Glycated Protein Biosensing Technology

“…Instead of reacting with fructosamines, these FN3K-related proteins (FN3K-RP) were found to react with C3 epimers, such as psicosamines, ribulosamines, and erythrulosamines. 30,31 FN3Ks/FN3K-RPs may be attractive sensing molecules since they have the ability to react with intact glycated proteins, however, the development of analytical methods employing FN3K/FN3K-RP have not yet been reported.…”

DETERMINATION OF ADVANCED GLYCATION (AGEs) AND LIPOXIDATION (ALEs) END PRODUCTS IN FOODS AND BIOLOGICAL SYSTEMS: ADVANCES, CHALLENGES AND PERSPECTIVES

“…A reação de reversão não enzimática produz glicose e manose, enquanto a reversão enzimática envolve a fosforilação do produto de Amadori, acompanhada de liberação de 3-desoxiglicosona (3-DG). 30,31 Em contraste, as reações de conversão são mais complexas e geram uma variada gama de compostos carbonílicos e dicarbonílicos, livres ou ligados à proteínas e envolvendo reações análogas às que ocorrem nos alimentos, gerando assim os AGEs. 23 Em adição ao processo de glicação de proteínas propriamente dito, outros mecanismos que contribuem para a formação de AGEs/ ALEs já foram identificados em condições fisiológicas, sendo eles a fragmentação da base de Schiff, a degradação da frutosamina, a…”