The high-resolution NMR structure of the R21A Spc-SH3:P41 complex: Understanding the determinants of binding affinity by comparison with Abl-SH3

Background  

SH3 domains are small protein modules of 60–85 amino acids that bind to short proline-rich sequences with moderate-to-low affinity and specificity. Interactions with SH3 domains play a crucial role in regulation of many cellular processes (some are related to cancer and AIDS) and have thus been interesting targets in drug design. The decapeptide APSYSPPPPP (p41) binds with relatively high affinity to the SH3 domain of the Abl tyrosine kinase (Abl-SH3), while it has a 100 times lower affinity for the α-spectrin SH3 domain (Spc-SH3).     

Subtype selective NMDA receptor antagonists: evaluation of some novel alkynyl analogues

A benzylpiperidine analogue with an acetylenic linker, 5-(3-[4-(4-fluorobenzyl)-piperidin-1-yl]-prop-1-ynyl)-1,3-dihydrobenzimidazol-2-one (3), was identified as a chemical lead with excellent activity at the NR1A/2B receptor (IC50=3 nM). Efforts to optimize this activity led to focused modifications around the structural motif of 3. The synthesis and SAR studies are discussed.     

The dnaA protein of Escherichia coli. Abundance, improved purification, and membrane binding

Immunoassays of dnaA protein in extracts from five strains showed a rather constant abundance relative to cell mass, with a variation of 800-2100 molecules/cell; overproducing cells contained 100-fold that number. About half of the dnaA protein in wild type cells was solubilized by a lysis procedure. Within the insoluble fractions, dnaA protein was identified by its characteristic high-affinity binding of ATP. An improved, rapid procedure for purifying dnaA protein from overproducing cells appears to depend on its coprecipitation with phospholipids and depends on solubilization by guanidine HCl. The procedure, with a 5-fold increased yield, also eliminates a potent ATPase contaminant. Purified dnaA protein, unlike dnaB and dnaC proteins, binds to phospholipid vesicles as judged by analysis on sucrose gradient centrifugation.