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It is proposed to perform quantum mechanical/molecular dynamics calculations of chemical reactions that are planned to be catalyzed by antibodies and then conduct a virtual screening of the library of potential antibody mutants to select an optimal biocatalyst. We tested the effectiveness of this approach by the example of hydrolysis of organophosphorus toxicant paraoxon using kinetic approaches and X-ray analysis of the antibody biocatalyst designed de novo.

In striated muscles, molecular filaments are largely composed of long protein chains with extensive arrays of identically folded domains, referred to as “beads-on-a-string”. It remains a largely unresolved question how these domains have developed a unique molecular profile such that each carries out a distinct function without false-positive readout. This study focuses on the M-band segment of the sarcomeric protein titin, which comprises ten identically folded immunoglobulin domains. Comparative analysis of high-resolution structures of six of these domains ‒ M1, M3, M4, M5, M7, and M10 ‒ reveals considerable structural diversity within three distinct loops and a non-conserved pattern of exposed cysteines. Our data allow to structurally interpreting distinct pathological readouts that result from titinopathy-associated variants. Our findings support general principles that could be used to identify individual structural/functional profiles of hundreds of identically folded protein domains within the sarcomere and other densely crowded cellular environments.

Expression of insulin-like growth factor 1 (IGF-1) mRNAs splice forms was recently shown to be stimulated by myofibrillar proteins released from the damaged muscle. In this study, we report that individual subfragments of titin and myomesin composed of Fn type III and Ig-like domains can activate expression of two IGF-1 splice forms in cultured myoblasts, both at protein and mRNA levels. Competition studies showed that each of the domain-types interacts with its own receptor. Induction of IGF-1 expression caused by domains of different types showed dissimilar sensitivity to inhibitors of regulatory cascades. The effect of Fn type III domains was more sensitive to inhibition of Ca(2+)/calmodulin dependent protein kinase, whereas the effect of Ig-like domains showed greater sensitivity to the inhibition of the adenylyl cyclase-cAMP-PKA pathway.

The Zn[(OPPh2)(SePPh2)N]2 complex was prepared by a metathetical reaction between a Zn(II) salt and the deprotonated form of the dichalcogenoimidodiphosphinato ligand [(OPPh2)(SePPh2)N]−. X-ray crystallography revealed a pseudo-tetrahedral MO2Se2 coordination sphere, owed to the asymmetric (O,Se) nature of the chelating ligand. A comparison between the structural features of the M[(OPPh2)(SePPh2)N]2 complexes, M = Co, Ni, Zn, shows that the three complexes are isomorphous. The IR and 31P NMR properties of Zn[(OPPh2)(SePPh2)N]2 are analyzed in the framework of its crystallographic structure, and are compared with data on similar systems. The above three complexes, along with the (OPPh2)(SePPh2)NH ligand and SeO2, are investigated as inhibitors of the Platelet Activating Factor (PAF) and thrombin activities. The paramagnetic M[(OPPh2)(SePPh2)N]2 complexes, M = Co, Ni, exhibit an approximately 65-fold increased activity, compared to diamagnetic Zn[(OPPh2)(SePPh2)N]2, in both the PAF- and the thrombin-induced aggregation of washed rabbit platelets (WRP). The above three complexes show a comparable significant inhibitory activity in the PAF-induced aggregation of rabbit platelet rich plasma (RPR). Remarkably, SeO2, a form of Se present in blood, exhibits a very strong and selective inhibitory activity towards the PAF-induced aggregation of WPR. Our studies extend the dataset of metal complexes investigated as inhibitors of PAF and thrombin.

The complete resolution of 2,2[prime or minute]-dihydroxy-1,1[prime or minute]-binaphthyl into its enantiomers by inclusion complexation with a commercially available derivative of choline, is reported. The two enantiomers are recovered in99% ee from the inclusion complexes by simple dissolution in a diethyl ether-water medium and the resolving agent can be recycled.