Friedman M, Gumbmann M R
Adv Exp Med Biol. 1986;199:357-89. doi: 10.1007/978-1-4757-0022-0_21.
Treatment of raw soy flour with L-cysteine or N-acetyl-L-cysteine results in the introduction of new half-cystine residues into sulfur-poor legume proteins, with a corresponding improvement in nutritional quality as measured by the protein efficiency ratio (PER) in rats. The proteins are modified through formation of mixed disulfide bonds among added sulfhydryl compounds, proteolytic enzyme inhibitors, and structural legume proteins. This modification leads to loss of inhibitory activity and increased protein digestibility and nutritive value. Sodium sulfite is more effective than cysteine in facilitating inactivation of trypsin inhibitors in soy flour. The synergistic effect of sodium sulfite and heat may be due to ability to induce rearrangement of protein disulfide bonds to produce new structural entities without altering the amino acid composition and to the fact that the new structures lose their ability to complex with trypsin or chymotrypsin. The same treatment inactivated hemagglutinins (lectins) in lima bean flour. These considerations suggest a key role for sulfur amino acids in the nutritional quality and safety of legumes.
用L-半胱氨酸或N-乙酰-L-半胱氨酸处理生大豆粉，会使新的半胱氨酸残基引入到硫含量低的豆类蛋白质中，通过大鼠的蛋白质效率比（PER）衡量，其营养质量相应提高。蛋白质通过添加的巯基化合物、蛋白水解酶抑制剂和豆类结构蛋白之间形成混合二硫键而发生修饰。这种修饰导致抑制活性丧失，蛋白质消化率和营养价值增加。亚硫酸钠在促进大豆粉中胰蛋白酶抑制剂失活方面比半胱氨酸更有效。亚硫酸钠和热的协同作用可能是由于其能够诱导蛋白质二硫键重排以产生新的结构实体而不改变氨基酸组成，以及新结构失去与胰蛋白酶或糜蛋白酶结合的能力。同样的处理使利马豆粉中的血凝素（凝集素）失活。这些考虑表明硫氨基酸在豆类的营养质量和安全性中起关键作用。
