Travis J, Owen M, George P, Carrell R, Rosenberg S, Hallewell R A, Barr P J
J Biol Chem. 1985 Apr 10;260(7):4384-9.
Using the glyceraldehyde-3-phosphate dehydrogenase promoter, nonglycosylated human alpha 1-proteinase inhibitor, representing 10% of the soluble cell protein, has been synthesized in yeast. Two forms of this protein were isolated with one being analogous to the human plasma protein and the other having the amino acid valine replacing methionine at position 358 (the P1 position). Both proteins were more sensitive to heat inactivation than the plasma form, and both had shorter half-lives in rabbits. These differences were presumably due to the absence of carbohydrate. Each protein could bind neutrophil elastase at a rate only slightly slower than that of human plasma alpha 1-proteinase inhibitor. However, the valine variant was stable to oxidation, while the P1 methionine-containing protein was readily inactivated. The specificity of alpha 1-proteinase inhibitor (methionine) was identical to that of the plasma form; however, the valine form could only effectively bind to neutrophil or pancreatic elastase, "trypsin-like" serine proteinases not being inactivated at all. These data indicate the potential importance of mutant forms of proteinase inhibitors, produced by recombinant DNA technology, as therapeutic agents for the inactivation of excess proteinases of a specific type in tissues.
利用甘油醛-3-磷酸脱氢酶启动子，已在酵母中合成了占可溶性细胞蛋白10%的非糖基化人α1-蛋白酶抑制剂。分离出了该蛋白的两种形式，一种类似于人血浆蛋白，另一种在358位（P1位）氨基酸缬氨酸取代了甲硫氨酸。这两种蛋白都比血浆形式对热失活更敏感，并且在兔体内的半衰期都较短。这些差异可能是由于缺乏碳水化合物。每种蛋白与中性粒细胞弹性蛋白酶结合的速率仅比人血浆α1-蛋白酶抑制剂略慢。然而，缬氨酸变体对氧化稳定，而含P1甲硫氨酸的蛋白则容易失活。α1-蛋白酶抑制剂（甲硫氨酸）的特异性与血浆形式相同；然而，缬氨酸形式只能有效地结合中性粒细胞或胰腺弹性蛋白酶，对“胰蛋白酶样”丝氨酸蛋白酶则完全没有失活作用。这些数据表明，通过重组DNA技术产生的蛋白酶抑制剂突变体形式作为使组织中特定类型的过量蛋白酶失活的治疗剂具有潜在的重要性。
