Ge S J, Zhang L X
Department of Biochemistry, College of Life Science, Peking University, Beijing, China.
Appl Biochem Biotechnol. 1996 May;59(2):159-65. doi: 10.1007/BF02787817.
The practical application of exopeptidase has been limited by the high cost of the enzymes resulting from the low content of individual exopeptidase in the raw material. This can be overcome by the use of a combination of all the exopeptidases in the same enzyme source, as well as the use of the enzyme immobilization technology. A porcine pancreatic exopeptidase mixture was prepared by the ammonium sulfate precipitation at 35% saturation of the autolyzed pancreatic juice. The enzyme preparation was immobilized on thin shrimp chitin film by crosslinking with glutaraldehyde. The immobilized porcine pancreatic exopeptidases (IPPE) was effective in releasing the free amino acids from peptides. Of these amino acids, the concentrations of arginine, lysine, histidine, tyrosine, phenylalanine, leucine, and glutamine were increased much more than those of other amino acids. This indicated that both the porcine pancreatic exopeptidases preparation and the IPPE contained carboxypeptidase A, B, and aminopeptidase. The IPPE was also efficient in the decrease of the hydrophobicity of protein hydrolysates demonstrated by hydrophobic chromatographic analysis. This led to the application of the immobilized exopeptidases in protein hydrolysate debittering. The IPPE was able to remove the bitterness of the tryptic/chymotryptic casein hydrolysates.
由于原料中单个外肽酶含量低导致酶成本高，外肽酶的实际应用受到限制。这可以通过在同一酶源中使用所有外肽酶的组合以及使用酶固定化技术来克服。通过对自溶胰液进行35%饱和度的硫酸铵沉淀制备猪胰外肽酶混合物。通过与戊二醛交联将酶制剂固定在薄虾壳聚糖膜上。固定化猪胰外肽酶（IPPE）能有效地从肽中释放游离氨基酸。在这些氨基酸中，精氨酸、赖氨酸、组氨酸、酪氨酸、苯丙氨酸、亮氨酸和谷氨酰胺的浓度比其他氨基酸增加得多。这表明猪胰外肽酶制剂和IPPE都含有羧肽酶A、B和氨肽酶。通过疏水色谱分析表明，IPPE在降低蛋白质水解物的疏水性方面也很有效。这导致固定化外肽酶在蛋白质水解物脱苦中的应用。IPPE能够去除胰蛋白酶/胰凝乳蛋白酶酪蛋白水解物的苦味。
