Paul S, Volle D J, Powell M J, Massey R J
Department of Pharmacology, University of Nebraska Medical Center, Omaha 68105.
J Biol Chem. 1990 Jul 15;265(20):11910-3.
Ten fragments of vasoactive intestinal peptide (VIP) were tested for reactivity with a human catalytic autoantibody that cleaves full-length VIP(1-28) at the Gln16-Met17 peptide bond. A large COOH-terminal subsequence, VIP(15-28), was bound by the autoantibody with high affinity (Ki 1.25 nM), suggesting that it is the antibody binding epitope. VIP(22-28), a short subsequence distant from the scissile bond, inhibited the binding (Ki 242 microM) and hydrolysis (Ki 260 microM) of full-length VIP by the catalytic autoantibody in a competitive fashion. The autoantibody did not show detectable binding of short VIP subsequences that encompass the scissile bond (VIP(15-21), VIP(11-17), and VIP(13-20]. These data show that residues 22-28, located four amino acids distant from the scissile bond, contribute in recognition of VIP by the catalytic autoantibody.
对十种血管活性肠肽（VIP）片段进行了测试，以检测它们与一种人类催化自身抗体的反应性，该自身抗体在Gln16 - Met17肽键处切割全长VIP(1 - 28)。一个大的COOH末端亚序列VIP(15 - 28)以高亲和力（Ki 1.25 nM）与自身抗体结合，表明它是抗体结合表位。VIP(22 - 28)，一个远离裂解键的短亚序列，以竞争方式抑制催化自身抗体对全长VIP的结合（Ki 242 microM）和水解（Ki 260 microM）。该自身抗体未显示出对包含裂解键的短VIP亚序列（VIP(15 - 21)、VIP(11 - 17)和VIP(13 - 20)）的可检测结合。这些数据表明，位于距裂解键四个氨基酸处的22 - 28位残基有助于催化自身抗体对VIP的识别。
