A molecular mechanism for the enzymatic methylation of nitrogen atoms within peptide bonds.

The peptide bond, the defining feature of proteins, governs peptide chemistry by abolishing nucleophilicity of the nitrogen. This and the planarity of the peptide bond arise from the delocalization of the lone pair of electrons on the nitrogen atom into the adjacent carbonyl. While chemical methylation of an amide bond uses a strong base to generate the imidate, OphA, the precursor protein of the fungal peptide macrocycle omphalotin A, self-hypermethylates amides at pH 7 using -adenosyl methionine (SAM) as cofactor.

Stabilization of activated fragments by shell-wise construction of an embedding environment.

An activated fragment which is structurally unstable when considered isolated can be stabilized through binding to a suitable molecular environment; for instance, to a transition-metal fragment. The metal fragment may be designed in a shell-wise build-up of a surrounding molecular environment. However, adding more and more atoms in a consecutive fashion soon leads to a combinatorial explosion of structures, which is unfeasible to handle without automation.

Calculated Resonance Vibrational Raman Optical Activity Spectra of Naproxen and Ibuprofen.

Determining the absolute configuration of a molecule is possible by means of various chiroptical spectroscopic methods, one of them being vibrational Raman optical activity (VROA). By adopting a laser excitation wavelength in resonance with an electronic transition, the weak spectral signals can be selectively enhanced. We implement a Kohn-Sham methodology for the calculation of resonance and off-resonance VROA spectra to (S)-naproxen and (S)-ibuprofen and discuss their band patterns.