Mistry R, Snashall P D, Totty N, Briskin S, Guz A, Tetley T D
Department of Medicine, Charing Cross and Westminster Medical School, London, UK.
Biochim Biophys Acta. 1997 Sep 26;1342(1):51-61. doi: 10.1016/s0167-4838(97)00086-1.
A Kazal-type elastase inhibitor was purified by trichloroacetic acid precipitation of sheep lung lavage fluid followed by chymotrypsin affinity and gel-filtration chromatography of the supernatant. Sheep lung elastase inhibitor (SLEI) is glycosylated. Laser desorption mass spectrometry indicated that SLEI has a molecular mass of 16.8-17.3 kDa. Partial protein sequence of SLEI and of a peptide derived from SLEI showed 31-52% and 51-66% homology at the N-terminus and at the inhibitory site respectively with Kazal-type double-headed proteinase inhibitors (bikazins). SLEI inhibited human leukocyte elastase and porcine pancreatic elastase but not human cathepsin G. It was inactivated by chloramine-T and reactivated when incubated with methionine sulfoxide peptide reductase and dithiothreitol, indicating the presence of a methionine at the active site. The concentration of SLEI in bronchoalveolar lavage fluid (BALF) and lung lymph was 0.28 microM (0.23-0.49); 0.24 microM (0.20-0.31) (median, (range), n = 5), respectively and was undetectable in plasma (< 0.03 microM) suggesting that SLEI is produced in the lung. The median molar ratios of SLEI to alpha1-proteinase inhibitor in BALF and lung lymph were 3.2 to 1 and 0.017 to 1, respectively. These results indicate that SLEI probably makes an important contribution to antielastase defence in epithelial lining liquid.
通过用三氯乙酸沉淀羊肺灌洗液，然后对上清液进行胰凝乳蛋白酶亲和色谱和凝胶过滤色谱，纯化了一种卡扎尔型弹性蛋白酶抑制剂。羊肺弹性蛋白酶抑制剂（SLEI）是糖基化的。激光解吸质谱表明SLEI的分子量为16.8 - 17.3 kDa。SLEI及其衍生肽的部分蛋白质序列在N端和抑制位点分别与卡扎尔型双头蛋白酶抑制剂（双卡津）显示出31 - 52%和51 - 66%的同源性。SLEI抑制人白细胞弹性蛋白酶和猪胰弹性蛋白酶，但不抑制人组织蛋白酶G。它被氯胺 - T灭活，并在与甲硫氨酸亚砜肽还原酶和二硫苏糖醇孵育时重新激活，表明活性位点存在甲硫氨酸。支气管肺泡灌洗液（BALF）和肺淋巴中SLEI的浓度分别为0.28 microM（0.23 - 0.49）；0.24 microM（0.20 - 0.31）（中位数，（范围），n = 5），而在血浆中未检测到（< 0.03 microM），这表明SLEI是在肺中产生的。BALF和肺淋巴中SLEI与α1 - 蛋白酶抑制剂的摩尔比中位数分别为3.2比1和0.017比1。这些结果表明SLEI可能在上皮衬液的抗弹性蛋白酶防御中起重要作用。
