作者: Ulrika Brath , Mikael Akke
DOI: 10.1016/J.JMB.2009.01.047
关键词: Transition state analog 、 Enzyme catalysis 、 Active site 、 Stereochemistry 、 Side chain 、 Isomerase 、 Protein structure 、 Target protein 、 Chemistry 、 Ground state
摘要: FKBP12 serves a dual role as peptidyl-prolyl cis-trans isomerase and modulator of several cell signaling pathways. The macrolide FK506 is transition-state analog the catalyzed reaction displaces from its natural target proteins. We compared conformational exchange dynamics backbone methyl-bearing side chains in free FK506-bound states using NMR relaxation-dispersion experiments. Our results show that enzyme exchanges between ground state an excited resembles ligand-bound or Michaelis complex. In FKBP12, confined to single conformation, while prevails for many methyl groups. residual side-chain analog-bound suggests ensemble involves multiple conformations, finding challenges long-standing concept restriction Furthermore, alternative conformations observed bound extended network groups includes locations remote active site. Several these are known be important interactions with cellular proteins, including calcineurin ryanodine receptor, suggesting heterogeneity might play promiscuous binding different targets.