Peptide Selection for Accurate Targeted Protein Quantification via a Dimethylation High-Resolution Mass Spectrum Strategy with a Peptide Release Kinetic Model.

A crucial step in accurate targeted protein quantification using targeted proteomics is to determine optimal proteotypic peptides representing targeted proteins. In this study, a workflow of peptide selection to determine proteotypic peptides using a dimethylation high-resolution mass spectrum strategy with a peptide release kinetic model was investigated and applied in peptide selection of bovine serum albumin. After specificity, digestibility, recovery, and stability evaluation of tryptic peptides in bovine serum albumin, the optimal proteotypic peptide was selected as LVNELTEFAK.

Engineering the Enantioselectivity of Yeast Old Yellow Enzyme OYE2y in Asymmetric Reduction of (/)-Citral to ()-Citronellal.

The members of the Old Yellow Enzyme (OYE) family are capable of catalyzing the asymmetric reduction of (/)-citral to ()-citronellal-a key intermediate in the synthesis of L-menthol. The applications of OYE-mediated biotransformation are usually hampered by its insufficient enantioselectivity and low activity. Here, the ()-enantioselectivity of Old Yellow Enzyme from CICC1060 (OYE2y) was enhanced through protein engineering.

Characterization of a Carbonyl Reductase from WZ010 and Its Variant Y54F for Asymmetric Synthesis of ()--Boc-3-Hydroxypiperidine.

The recombinant carbonyl reductase from WZ010 (ReCR) demonstrated strict ()-stereoselectivity and catalyzed the irreversible reduction of -Boc-3-piperidone (NBPO) to ()--Boc-3-hydroxypiperidine [()-NBHP], a key chiral intermediate in the synthesis of ibrutinib. The NAD(H)-specific enzyme was active within broad ranges of pH and temperature and had remarkable activity in the presence of higher concentration of organic solvents. The amino acid residue at position 54 was critical for the activity and the substitution of Tyr54 to Phe significantly enhanced the catalytic efficiency of ReCR.

Selection of marker peptides from casein phosphopeptide and application for quantification in infant formula.

Casein phosphopeptides (CPPs) have been used worldwide as a nutritional supplement. However, the peptide components have been unknown; as a consequence, few quantification methods of CPP in infant formula were reported. This study introduced a quantification method based on peptide marker and corresponding peptide selection strategy using a simplified model with four commercial types of CPP.