Studies on the expression of methylglyoxal metabolizing enzymes and its relation to 2-acetyl-1-pyrroline biosynthesis in soybean

• Main Authors: Chi-Ruei Wu, 吳其叡
• Other Authors: Tzou-Chi Huang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/76585038458227282490

碩士 === 國立屏東科技大學 === 食品科學系所 === 95 === 2-acetyl-1-pyrroline (2AP) has been reported as a potent flavor component of popcorn, aromatic rice, vegetable soybean, pandan leaves. The nitrogen source of pyrroline of 2AP was proline, but the acetyl-group has not been well-characterized. According to the methylglyoxal metabolizing pathway, it has been hypothesized the methylglyoxal (MG) is the important intermediate product for acetyl-group in soybean, and concentration of MG is expected to be positively correlated to the 2AP level in soybean. MG is a kind of α-oxoaldehyde. It is synthesized either enzymatically or nonenzymatically. Exposure of cells to high concentrations of methylglyoxal, by addition of exogenousα-oxoaldehyde or inhibition of enzymatic detoxification, induces growth arrest and toxicity. In cells, methylglyoxal can be detoxified by glyoxalase system, aldose reductase, betaine aldehyde dehrdrogenase and glutathione-S-transferase. We have found that the aromatic soybean contains MG about 4.45 mM/g, which is higher than 4.09 mM/g in non-aromatic soybean. The expressions of MG metabolizing gene have been studied by RT-PCR. The variation in gene expression between aromatic and non-aromatic vegetable soybean seed has been compared. The MG detoxifying genes, including AR, BAD, Gly I, GST, were found to increase significantly in aromatic soybean. The level of 2AP in aromatic and non-aromatic soybean was quantified by GC/MASS and SPME. We purposed MG and P5C will lead to biosynthesis 2AP in aromatic soybean.