A novel Kazal-type trypsin inhibitor from the skin secretion of the Central American red-eyed leaf frog, Agalychnis callidryas

作者：Li, Renjie; Wang, Hui; Jiang, Yingchun; Yu, Yang; Wang, Lei^*; Zhou, Mei; Zhang, Yingqi; Chen, Tianbao; Shaw, Chris

来源：Biochimie, 2012, 94(6): 1376-1381.

DOI：10.1016/j.biochi.2012.03.009

• Amphibian
• Skin
• Peptide
• Protein
• Trypsin
• Inhibitor
• Cloning

The chemical complexity of the defensive skin secretion of the red-eyed leaf frog, (Agalychnis callidryas), has not been elucidated in detail. During a systematic study of the skin secretion peptidomes of phyllomedusine frogs, we discovered a novel Kazal-type protein with potent trypsin inhibitory activity (Ki = 1.9 nM) that displays the highest degree of structural similarity with Kazal proteins from bony fishes. The protein was located in reverse-phase HPLC fractions following a screen of such for trypsin inhibition and subsequent partial Edman degradation of the peak active fraction derived the sequence: ATKPR-QYIVL-PRILRPV-GT. The molecular mass of the major component in this fraction was established by MALDI-TOF MS as 5893.09 Da. This partial sequence (assuming blank cycles to be Cys residues) was used to design a degenerate primer pool that was employed successfully in RACE-PCR to clone homologous precursor-encoding cDNA that encoded a mature Kazal protein of 52 amino acid residues with a computed molecular mass of 5892.82 Da. The protein was named A. callidryas Kazal trypsin inhibitor (ACKTI). BLAST analysis revealed that ACKTI contained a canonical Kazal motif (C-x(7)-C-x(6)-Y-x(3)-C-x(2,3)-C). This novel amphibian skin Kazal trypsin inhibitor adds to the spectrum of trypsin inhibitors of Kunitz- and Bowman Birk-type reported from this amphibian source.

• 出版日期2012-6
• 单位唐山市工人医院