Influence of the phosphate buffer on DNA breaking activity of maillard reaction products of glucose-glycine system

• Main Authors: Chen,Ying-Chi, 陳盈吉
• Other Authors: Tsun,Chung Tsai
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/84703403655262952555

碩士 === 東海大學 === 食品科學系 === 86 === 1M glucose-glycine solutions heated at 100℃with various concentrations of phosphate buffer(initial pH 7.5). The results of the reactions indicated that the higher concentration of phosphate buffer used, the higher concentration of MRPs became(Browning index higher). And stronger the DNA Breaking Activity of MRPs produced. They are duplicates of the results of 1M glucose-glycine solutions incubated at 25℃ with various concentrations of phosphate buffer(initial pH 7.5). MRPs(H) produced in 1M glucose-glycine solutions heated at 100℃ in water for 48hr showed higher browning index. But the MRPs(P) produced in 1M glucose-glycine solutions heated at 100℃ with 1M phosphate buffer for few hours still have higher DNA Breaking Activity. There are three buffers(MOPS,BES,and phosphate buffers), when the initial pH value the same, concentrations the same, they have similar buffer capacity; because they have similar pKa value. Use these three buffers heating with 1M glucose-glycine solutions, we found the MRPs which made from 1M glucose-glycine solutions heated with phosphate buffer had the most strong DNA Breaking Activity. Contral the concentration of phosphate buffer, 1M glucose-glycine solutions heated at 100℃with various initial pH values of phosphate buffer(1M). The initial pH value lower, the reaction rate lower(Browning index lower). But DNA Breaking Activity were identical. The MRPs were prepared by refluxing 1M glucose-glycine in 1M phosphate(at 100℃ and pH 7.5) for 1hr and fractionated by membrane filters with various ranges of molecular weight cut off (MWCO). The molecular weight of the most MRPs were below 5,000. This major fraction was chromatograph into two bands by Sephadex G-25 column; and one(band 1) of them showed strong DNA Breaking Activity. By ashing method to analyze total phosphorus of the subfractions from G-25 column was not identical from the band 1 fractions. Most of the total phosphorus were inorganic phosphorus, that indicated the phosphate did not bounded to the MRPs. On the other hand, 1M glucose-glycine solutions heated at 100℃ in water(MRPs(H)) for 24hr、initial pH 7.5, had simillar browning index to that of MRPs heated in 1M phosphate buffer(MRPs(P)) for 1 hour. Two MRPs solutions were fractioned by Sephadex G-25 column, there were produce two differert results. MRPs(P) were separate into two bands; the band 1 had higher browning index, with maximum the absorption of 280nm and the higher DNA Breaking Activity. MRPs(H) were separate into three major bands; the band 1 had best browning index and the absorption of 280nm. But the greatest DNA Breaking Activity was appear in band 2. The fractions of MRPs were compared and investigated by Blue dextran; the molecular weight of the band 1, band 2 of MRPs(P),and band 2,band 3 of MRPs(H) were below 5,000. And the molecular weight of the band 1 of MRPs(H) was above 5,000. This result confirm the MRPs of MRPs(H) and MRPs(P) were different.-1 -aInfluence of the phosphate buffer on DNA breaking activity of maillard reaction products of glucose-glycine system