Resnick N M, Maloy W L, Guy H R, Zasloff M
Division of Human Genetics Children's Hospital of Philadelphia, Pennsylvania.
Cell. 1991 Aug 9;66(3):541-54. doi: 10.1016/0092-8674(81)90017-9.
The magainin peptides of Xenopus laevis are broad-spectrum antimicrobial agents. Upon discharge from the skin glands, these basic, amphipathic peptides are each further processed at a single Xaa-Lys bond into half-peptides by a cosecreted protease. We describe the characterization and purification to homogeneity of this endopeptidase from Xenopus skin. The enzyme is a metalloprotease 110 kd in size. Analyses of substrate specificity revealed that the endopeptidase recognizes peptides that share the ability to adopt an amphipathic, alpha-helical motif composed of at least 12 residues, with one face strongly hydrophobic. Cleavage occurs on the amino side of a specific lysine that must be precisely positioned relative to the hydrophobic face of the alpha helix. This enzyme, which we propose to call "magaininase," represents a novel class of endopeptidases that hydrolyzes peptides on the basis of specific secondary structure rather than primary amino acid sequence.
非洲爪蟾的爪蟾抗菌肽是广谱抗菌剂。从皮肤腺体分泌出来后，这些碱性两亲性肽各自在一个特定的Xaa-Lys键处被一种共分泌的蛋白酶进一步加工成半肽。我们描述了这种来自非洲爪蟾皮肤的内肽酶的特性鉴定以及纯化至同质的过程。该酶是一种大小为110kd的金属蛋白酶。对底物特异性的分析表明，这种内肽酶识别那些具有形成由至少12个残基组成的两亲性α-螺旋基序能力的肽，其中一面具有很强的疏水性。切割发生在一个特定赖氨酸的氨基侧，该赖氨酸必须相对于α-螺旋的疏水面向精确定位。我们提议将这种酶称为“爪蟾抗菌肽酶”，它代表了一类新型的内肽酶，这类酶基于特定的二级结构而非一级氨基酸序列来水解肽。
