Reconstitution of the alternative pathway of the complement system enables rapid delineation of the mechanism of action of novel inhibitors.

The complement system plays a critical role in the innate immune response, acting as a first line of defense against invading pathogens. However, dysregulation of the complement system is implicated in the pathogenesis of numerous diseases, ranging from Alzheimer's to age-related macular degeneration and rare blood disorders. As such, complement inhibitors have enormous potential to alleviate disease burden.

A NOVEL EQUATION SUCCESSFULLY CALCULATES TIDAL VOLUMES FOR LUNG PROTECTIVE VENTILATION.

Background: Early application of low-tidal-volume ventilation (LTVV) has been associated with improved outcomes in the emergency department (ED) and intensive care unit (ICU), but is not consistently applied. The perceived complexity of calculating an ideal body weight (IBW)-based tidal volume (Vt) may contribute to this disparity. We hypothesized that a simplified equation could successfully predict LTVV.

A Versatile Approach to Noncanonical, Dynamic Covalent Single- and Multi-Loop Peptide Macrocycles for Enhancing Antimicrobial Activity.

Peptide oligomers offer versatile scaffolds for the formation of potent antimicrobial agents due to their high sequence versatility, inherent biocompatibility, and chemical tunability. Though many methods exist for the formation of peptide-based macrocycles (MCs), increasingly pervasive in commercial antimicrobial therapeutics, the introduction of multiple looped structures into a single peptide oligomer remains a significant challenge. Herein, we report the utilization of dynamic hydrazone condensation for the versatile formation of single-, double-, and triple-loop peptide MCs using simple dialdehyde or dihydrazide small-molecule cross-linkers, as confirmed by MALDI-TOF MS, HPLC, and SDS-PAGE.

Molecular impact of covalent modifications on nonribosomal peptide synthetase carrier protein communication.

Nonribosomal peptide synthesis involves the interplay between covalent protein modifications, conformational fluctuations, catalysis, and transient protein-protein interactions. Delineating the mechanisms involved in orchestrating these various processes will deepen our understanding of domain-domain communication in nonribosomal peptide synthetases (NRPSs) and lay the groundwork for the rational reengineering of NRPSs by swapping domains handling different substrates to generate novel natural products. Although many structural and biochemical studies of NRPSs exist, few studies have focused on the energetics and dynamics governing the interactions in these systems.

Solution Structure of a Nonribosomal Peptide Synthetase Carrier Protein Loaded with Its Substrate Reveals Transient, Well-Defined Contacts.

Nonribosomal peptide synthetases (NRPSs) are microbial enzymes that produce a wealth of important natural products by condensing substrates in an assembly line manner. The proper sequence of substrates is obtained by tethering them to phosphopantetheinyl arms of holo carrier proteins (CPs) via a thioester bond. CPs in holo and substrate-loaded forms visit NRPS catalytic domains in a series of transient interactions.

A nuclear magnetic resonance method for probing molecular influences of substrate loading in nonribosomal peptide synthetase carrier proteins.

Carrier proteins (CPs) play a central role in nonribosomal peptide synthetases (NRPSs) as they shuttle covalently attached substrates between active sites. Understanding how the covalent attachment of a substrate (loading) influences the molecular properties of CPs is key to determining the mechanism of NRPS synthesis. However, structural studies have been impaired by substrate hydrolysis.

NMR methods for structural studies of large monomeric and multimeric proteins.

NMR structural studies of large monomeric and multimeric proteins face distinct challenges. In large monomeric proteins, the common occurrence of frequency degeneracies between residues impedes unambiguous assignment of NMR signals. To overcome this barrier, nonuniform sampling (NUS) is used to measure spectra with optimal resolution within reasonable time, new correlation maps resolve previous impasses in assignment strategies, and novel selective methyl labeling schemes provide additional structural probes without cluttering NMR spectra.