グルコースとアンモニアとの室温における非酵素的反応 : その反応の生理的意味
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概要
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Since Rahbar (1968) has found that HbA_<1C>, which was later found to be glycosylated, increases in the blood of patients suffering from diabetes mellitus. the nonenzymatic glycosylation of biologically relevant molecules has become an increasingly important working hypothesis toward unraveling some of corrmlications associated with diabetes mellitus and aging. This study has begun when ninhydrin-reactive compound (NR compound)was found to be produced at room temperature as soon as glucose and dibasic ammonium phosphate solutions were mixed. The reaction seemed to be similar to Maillard reaction. The last report showed that the peak of the NR compound observed by amino acid analyzer is Amadori product of Maillard reaction, 1-amino-1-deoxyf ructose. Therefore, the experiments have been performed to purify the compound and examine if the compound plays any physiological role in mammals. A) In vitro experiments 1) Purification of NR compound : The reaction mixture of glucose and dibasic ammonium phosphate solutions was desalted in MicroAcilyzer and applied on cation-exchange resin, Dowex 50W-X8 column (Hナ)at DH2.0 to eliminate elucose. The NR compound adsorbed to the resin was eluted with 3.0N HCl solution. Finally, the residual salt in the eluent was removed by gel-filtration method with Sephadex G-10 column and the eluent containing NR compound thus obtained have no glucose and almost no salts. The peak of the NR compound was determined by amino acid analyzer. 2) Efficiency to produce ninhydrin-reactive compound of various sugars and various ammonium salts : In order to know the efficiency of various sugars and various ammonium salts to produce ninhydrin-reactive compound, the experiments were performed in combination of dibasic ammonium phosphate with each one of the various sugars and of glucose with each one of the various ammonium phosphates. The ninhydrin-reactive compound formed was quantitatively determined in amino acid analyzer. The results indicate that dibasic ammonium phosphate was most reactive among the ammonium salts used and glucose was most reactive among the sugars used. B) In vivo experiments 1) Effect of NR compound on bacteria : NR compound did not affect the growth rate of Excherichia coli K12, strain W3110 (prototroph, λ^-, F^-) and W4627 (F^-, trpB^-, lac^-, Sm^r). 2) Effect of NR compound on mice : NR compound injected into mice intraperitoneally did not show any recognizable effect on mice. Some of the mice was bled at l hr after injection, and the blood was subjected to・amino acid analyzer. But no NR compound was detected. 3) Determination of NR compound in sera of patients : Analysis by amino acid analyzer showed that deproteinized serum of a patient who was suffering from hepatocirrhosis and hyperammonemia (twice of normal level), gave a small peak at the same retention time as that of NR compound. However, sera from two patients who was suffering from hepatocirrhosis. but not from hyperammonemia gave no such peak. These results indicate that the compound has neither inhibitory effect nor accelerated effect on the bacterial erowth and no toxic effect on the mice. Rather, the compound seems to be broken down rapidly in the mice. However, since apparent N]R compound was found in a patient suffering from hepatic coma due to hyperammonemia caused by liver cirrhosis, NR compound is possibly formed in patients with hyperglycemia and/ or hyperammonemia and can play some physiological role in the patients. Not only in patients but also in normal subjects, the level of ammonia in portal vein is rather high and NR compound is possibly formed in the vein that affects the liver function in an unknown way.
- 北陸学院短期大学の論文
- 1995-12-28
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- グルコースとアンモニアとの室温における非酵素的反応 : その反応の生理的意味
- グルコースとアンモニアとの室温における非酵素的反応 : その反応機構