Front Cover. Creams and other cosmetics are often applied to reduce the visible ageing effects, such as facial wrinkles. Argireline, an acetyl hexapeptide Ac-Glu-Glu-Met-Gln-Arg-Arg-NH₂, sometimes described as ‘needle-free Botox' is often added to higher-end anti-wrinkle cosmetic products. However, detection and quantification of argireline content in commercially available cosmetics is complicated due to the low concentration and very complex matrix. The application of such sensitive method as LC-MS may not be enough to detect argireline in some products, moreover, the experiments revealed that the methionine residue is often oxidized, which may affect its biological properties in unexpected and as of yet uninvestigated ways, as reported by Kluczyk et al. in their full paper at 10.1002/cbdv.202000992.

Front Cover. TAP transporter is a key component of the MHC class I-restricted antigen presentation pathway, shuttling antigenic peptides across the ER membrane. BoHV-1 herpesvirus-encoded UL49.5 protein is a viral TAP inhibitor. Searching for the molecular mechanism of UL49.5 action, variations in the RRE(9-11) motif of its N-terminal domain were designed to abolish (RRE(9-11)GGG) or stabilize (RRE(9-11)AAA and RRE(9-11)E11G) the structure of the α-helix. The desired structural alterations were confirmed by circular dichroism, NMR, and molecular dynamics in membrane-mimetic environments. The introduced RRE modifications slightly altered the biological activity of UL49.5 in human cells, as demonstrated by MHC I level measurements by flow cytometry; yet, they could not abolish the UL49.5-mediated peptide transport arrest. The results indicate that other structural motifs may contribute to TAP inhibition as reported by Karska et al. in their full paper at 10.1002/cbdv.202000883.

Cover Picture. The primary function of acylpeptide hydrolase is associated with the removal of N-acetylated amino acid residues from proteins and peptides. Considering the protein degradation cycle cross-talk between acylpeptide hydrolase and proteasome, inhibition of the first enzyme resulted in down-regulation of the ubiquitin-proteasome system and induction of cancer cell apoptosis as reported by Maciej Walczak et al. in their full paper at10.1002/cbdv.202001004.

Front Cover. A new C-nucleoside with strongly pairing ethynylmethylpyridone base and 3'-azido-2',3'-dideoxyribose sugar dubbed 'AZW' was described. The image shows the structure of AZW against a backdrop of AZT in dotted cloud representation. The new nucleoside shows inhibitory activity against Herpes simplex virus type 1 (HSV1) as reported by Richert et al. in their full paper at10.1002/cbdv.202000937.