Capocchi A, Cinollo M, Galleschi L, Saviozzi F, Calucci L, Pinzino C, Zandomeneghi M
Dipartimento di Scienze Botaniche, Universita di Pisa, Italy.
J Agric Food Chem. 2000 Dec;48(12):6271-9. doi: 10.1021/jf0006170.
Vital gluten was used as an ideal substrate to investigate the role of some proteases in storage protein degradation. Aspartic proteinase and carboxypeptidase were identified as endogenous enzymes adsorbed on gluten and their optimum pH values determined. SDS-PAGE of soluble products released by gluten digestion revealed that the activity of these proteases plays a minor role in protein mobilization, whereas cysteine proteinase, purified from wheat seeds at the fourth day of germination, is extremely effective, producing a remarkable protein degradation in short times. Synergistic effects of aspartic and cysteine proteinase were not observed. Spin labeling of the sulfhydryl groups of gluten proteins enabled a comparative EPR investigation of the consequences of proteolytic degradation on gluten elasticity. It was found that storage protein mobilization brings a loss of elasticity to the polymeric network of gluten, which is particularly marked when the hydrolysis is performed by cysteine proteinase.
以活性谷蛋白作为理想底物，研究某些蛋白酶在贮藏蛋白降解中的作用。天冬氨酸蛋白酶和羧肽酶被鉴定为吸附在谷蛋白上的内源酶，并测定了它们的最佳pH值。谷蛋白消化释放的可溶性产物的SDS - PAGE分析表明，这些蛋白酶的活性在蛋白质动员中起次要作用，而从发芽第4天的小麦种子中纯化得到的半胱氨酸蛋白酶则极其有效，能在短时间内产生显著的蛋白质降解。未观察到天冬氨酸蛋白酶和半胱氨酸蛋白酶的协同作用。对谷蛋白的巯基进行自旋标记，能够通过电子顺磁共振对蛋白水解降解对谷蛋白弹性的影响进行比较研究。结果发现，贮藏蛋白的动员使谷蛋白聚合物网络的弹性丧失，当由半胱氨酸蛋白酶进行水解时，这种弹性丧失尤为明显。
