COVALENT STRUCTURE OF HUMAN HAPTOGLOBIN - A SERINE PROTEASE HOMOLOG
COVALENT STRUCTURE OF HUMAN HAPTOGLOBIN - A SERINE PROTEASE HOMOLOG
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DOI：
10.1073/pnas.77.6.3388
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发表时间：
1980-01-01
期刊：
影响因子：
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通讯作者：
FITCH, WM
中科院分区：
文献类型：
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作者：
KUROSKY, A;BARNETT, DR;FITCH, WM
建立了人结合珠蛋白1-1的完整氨基酸序列和2条链的二硫键排列。α1和β。结合珠蛋白的链分别含有83个和245个残基。结合珠蛋白的一级结构与丝氨酸蛋白酶的凝乳酶原家族的一级结构的比较显示出显著的化学相似性。β的化学相似性的概率小于10-5。结合珠蛋白与蛋白水解酶的结合是偶然的。β蛋白的氨基酸序列。结合珠蛋白链与牛胰蛋白酶、牛胰凝乳蛋白酶、猪弹性蛋白酶、人凝血酶或人纤溶酶的同源性为29%-33%。结合珠蛋白α1链与酶原激活肽的同源性为25%，与纤溶酶原激活肽的第5 kringle区同源性为25%。这种相似性是偶然的，概率不到0.014。结合珠蛋白显然是凝乳酶原丝氨酸蛋白酶家族的同系物。结合珠蛋白的β链序列与丝氨酸蛋白酶的比对非常一致，除了在与丝氨酸蛋白酶的甲硫基环相对应的区域插入了16个残基之外。结合珠蛋白中典型的丝氨酸蛋白酶活性中心残基组氨酸-57和丝氨酸-195分别被赖氨酸和丙氨酸取代；天冬氨酸-102和胰酶特异性残基天冬氨酸-189确实存在于结合珠蛋白中。结合珠蛋白和丝氨酸蛋白酶代表了具有不同生物功能的同源蛋白的显著例子。
The complete amino acid sequences and the disulfide arrangements of the 2 chains of human haptoglobin 1-1 were established. The .alpha.1 and .beta. chains of haptoglobin contain 83 and 245 residues, respectively. Comparison of the primary structure of haptoglobin with that of the chymotrypsinogen family of serine proteases revealed a significant degree of chemical similarity. The probability was less than 10-5 that the chemical similarity of the .beta. chain of haptoglobin to the proteases was due to chance. The amino acid sequence of the .beta. chain of haptoglobin is 29-33% identical to bovine trypsin, bovine chymotrypsin, porcine elastase, human thrombin, or human plasmin. Comparison of haptoglobin .alpha.1 chain to activation peptide regions of the zymogens revealed an identity of 25% to the 5th kringle region of the activation peptide of plasminogen. The probability was less than 0.014 that this similarity was due to chance. Haptoglobin is apparently a homolog of the chymotrypsinogen family of serine proteases. Alignment of the .beta.-chain sequence of haptoglobin to the serine proteases is remarkably consistent except for an insertion of 16 residues in the region corresponding to the methionyl loop of the serine proteases. The active-site residues typical of the serine proteases, histidine-57 and serine-195, are replaced in haptoglobin by lysine and alanine, respectively; aspartic acid-102 and the trypsin specificity residue, aspartic acid-189, do occur in haptoglobin. Haptoglobin and the serine proteases represent a striking example of homologous proteins with different biological functions.