A certified 28.3% efficient monolithic perovskite-silicon tandem (PST) solar cell with a mixed self-assembled monolayer (SAM) containing carbazole cores with H-ligands (2PACz) and methoxy-ligands (MeO-2PACz) is reported. Our analysis revealed that there existed uncovered areas of MeO-2PACz on indium tin oxide, which would be caused by the steric effect, and they were filled with 2PACz in the mixed SAM, leading to the improvement of fill factors in the PST cells. This result was explained by the passivation qualities as hole transport layers and the local interaction between methoxy ligands and perovskite materials.

D-glutamate, an indispensable component of peptidoglycans of bacteria, is provided by glutamate racemase in E. coli cells. Compensation for D-glutamate auxotrophy of E. coli WM335 cells lacking the glutamate racemase gene, murI, with the D-amino acid aminotransferase gene suggests that presence of a threshold concentration for the D-glutamate required by E. coli cells, as well as a regulation system for murI expression.

We studied the catalytic role of leucine 201 residue of the thermostable D-amino acid aminotransferase: the residue was shown crystallographically to be in the vicinity of the active site to interact with the bound pyridoxal phosphate. We replaced the leucine 201 by alanyl or tryptophanyl residues by means of site-directed mutagenesis. The L201A and L201W mutant enzymes showed anomalous kinetic behavior in the overall reaction. The reaction rates of the L201A and L201W mutant enzymes gradually decreased with an increase in the reaction time to become practically zero at a high concentration of substrates. The mutant enzymes were also inactivated in the half reaction with D-alanine, although more slowly than in the overall reaction. The absorption spectra of the mutant enzymes in the presence of D-alanine and alpha-ketoglutarate suggest that the enzyme molecules were mostly in the pyridoxamine form under the conditions employed. These phenomena were explained by assuming two (or more) enzyme species showing kinetically different catalysis for pyridoxamine form of the mutant enzymes, and the rate of conversion from one of these pyridoxamine forms to the pyridoxal form should be very low. The leucine 201 residue probably regulates the function of cofactor during the reaction of D-amino acid aminotransferase.