• 作者： 宋賢一; 陳賢哲; 莊淑貞
• 作者服務機構： 國立臺灣大學農業化學系
• 中文摘要： 市售烘焙用酵母（Saccharomyces spp.）用球磨機充分磨碎破壞細胞壁後，加人10倍量的1 % (w/v)三偏磷酸鈉(Sodi-um trimetaphosphate)水溶液，在pH 12及40℃攪拌一小時抽出可溶性蛋白質成分，離心後，上層液繼續於相同條件下進行蛋白質的化學磷酸化修飾反應。最後用2N鹽酸調至pH 4沈澱回收蛋白質，並經水洗、中和及冷凍乾燥，可得磷酸化酵母蛋向質分離物。由產品性質分析知在處理3小時後，酵母蛋白質分子與三偏磷酸鈉開始進行明顯的磷酸化反應，而將磷酸基以磷酯鍵結合至其絲胺酸殘基上。反應8小時後，約有1/3量的絲胺酸殘基已被磷酯化修飾且達成平衡。因為共價鍵結合之磷酸基的化學特性，使酵母蛋白質與核酸的複合物發生解離。酸沈澱回收之酵母蛋白質分離物中的核酸殘留量可由原先之33-36%降低至2.0-3.5％（w/w）左右。而且在中性水溶液中的溶解度及乳化性等機能性質也都有顯著的改善效果。此種化學磷酸化修飾技術可使酵母蛋白質分離物在食品加工中當做機能性配料利用的可行性大為提高。
• 英文摘要： Chemical phosphorylation in which sodium trimetaphosphate (STMP) was used in the modificationof protein in alkali was tried with the dual purpose to improve the functional properties and to reduce theresidual nucleic acid content of baker's yeast protein isolates. The mechanically disintegrated yeast cellswere subjected to a ten times by weight of 1% STMP aqueous solution (pH 12, 40℃) for the extraction ofyeast protein. After the supernatant was incubated for 8 hours under the same condition, the residualnucleic acid content of the acid-precipitated yeast protein isolates was significantly reduced from the origi-nal 33-36％(w/w, on the dry protein basis) to a minimum of 2.0-3.5％owing to the covalent attachmentof the anionic phosphate groups onto yeast protein. The functional properties of the phosphorylated yeastprotein isolates in terms of aqueous solubility and emulsifiability were much enhanced．
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