Au T K, Leung P C
Department of Zoology, University of Hong Kong.
Biochem Biophys Res Commun. 1995 Mar 8;208(1):280-6. doi: 10.1006/bbrc.1995.1335.
We report here that pituitary adenylate cyclase activating polypeptide (PACAP38), a new 38-residue neuropeptide of the secretin/glucagon family, is a potent inhibitor of calmodulin in vitro in the activation of bovine brain calmodulin-dependent cyclic nucleotide phosphodiesterase. The concentration of PACAP38 for half-maximal inhibition of the phosphodiesterase is 15 nM, one of the lowest for known calmodulin inhibitors. In the presence of Ca2+, PACAP38 binds strongly to calmodulin in a 1:1 ratio with a dissociation constant of about 28 nM. The binding is not dissociated by 4 M urea. In the absence of Ca2+ the binding is at random and can be dissociated by 4 M urea. Studies with PACAP38 derivatives show that the carboxyl half of the PACAP38 molecule is essential for the inhibition of calmodulin.
我们在此报告，垂体腺苷酸环化酶激活多肽（PACAP38），一种促胰液素/胰高血糖素家族的含38个氨基酸的新型神经肽，在体外是牛脑钙调蛋白依赖性环核苷酸磷酸二酯酶激活过程中钙调蛋白的强效抑制剂。磷酸二酯酶半数最大抑制浓度下的PACAP38浓度为15 nM，是已知钙调蛋白抑制剂中最低的之一。在Ca2+存在的情况下，PACAP38以1:1的比例与钙调蛋白强烈结合，解离常数约为28 nM。该结合不会被4 M尿素解离。在没有Ca2+的情况下，结合是随机的，并且可以被4 M尿素解离。对PACAP38衍生物的研究表明，PACAP38分子的羧基端对于抑制钙调蛋白至关重要。
