Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:3.4.21.4 (
trypsin
)
42,187
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Fructosamine-3-kinase
(
FN3K
) phosphorylates fructosamine residues, leading to their destabilization and their shedding from protein. Support for the occurrence of this deglycation mechanism in intact cells has been obtained by showing that hemoglobin is significantly more glycated when human erythrocytes are incubated with an elevated glucose concentration in the presence of 1-deoxy-1-morpholinofructose (DMF), a cell-permeable inhibitor of
FN3K
, than in its absence. The aim of this work was to identify the fructosamine residues on hemoglobin that are removed as a result of the action of
FN3K
in intact erythrocytes. Highly glycated hemoglobin derived from intact human erythrocytes incubated for 48 h with 200 mm glucose and DMF was incubated in vitro with
FN3K
and [gamma-(32)P]ATP. After reduction of fructosamine 3-phosphates with borohydride, the protein was digested with
trypsin
. Peptides were separated by reversed-phase high-performance liquid chromatography, and the radioactive peaks were analyzed by mass spectrometry. Nine different modified residues were identified. These were Lys-alpha-16, Lys-alpha-61, Lys-alpha-139, Val-beta-1, Lys-beta-17, Lys-beta-59, Lys-beta-66, Lys-beta-132, and Lys-beta-144. Some (e.g. Lys-alpha-139) were readily phosphorylated to a maximal extent by
FN3K
in vitro whereas others (e.g. Val-beta-1) were slowly and only very partially phosphorylated. The radiolabeled peptides containing reduced fructosamine 3-phosphates bound to Lys-alpha-16, Lys-alpha-139, and Lys-beta-17 were much less abundant if the hemoglobin substrate used for the in vitro phosphorylation with
FN3K
and [gamma-(32)P]ATP came from erythrocytes incubated with an elevated glucose concentration in the absence of DMF, indicating that these lysine residues had been substantially deglycated in intact cells when
FN3K
action was unrefrained. Other residues (e.g. Val-beta-1, Lys-alpha-61) seemed to be insignificantly deglycated in intact cells.
...
PMID:Identification of fructosamine residues deglycated by fructosamine-3-kinase in human hemoglobin. 1510 34
