High expression of human epidermal growth factor receptor 2 (HER2) in breast and gastroesophageal carcinomas is a predictive biomarker for treatment using HER2-targeted therapeutics (antibodies trastuzumab and pertuzumab, antibody-drug conjugate trastuzumab DM1, and tyrosine kinase inhibitor lapatinib). Radionuclide molecular imaging of HER2 expression might permit stratification of patients for HER2-targeting therapies. In this study, we evaluated a new HER2-imaging probe based on the designed ankyrin repeat protein (DARPin) 9_29. DARPin 9_29 was labeled with iodine-125 by direct radioiodination and with [99mTc]Tc(CO)3 using the C-terminal hexahistidine tag. DARPin 9_29 preserved high specificity and affinity of binding to HER2-expressing cells after labeling. Uptake of [125I]I-DARPin 9_29 and [99mTc]Tc(CO)3-DARPin 9_29 in HER2-positive SKOV-3 xenografts in mice at 6 h after injection was 3.4 ± 0.7 %ID/g and 2.9 ± 0.7 %ID/g, respectively. This was significantly (p < 0.00005) higher than the uptake of the same probes in HER2-negative Ramos lymphoma xenografts, 0.22 ± 0.09 %ID/g and 0.30 ± 0.05 %ID/g, respectively. Retention of [125I]I-DARPin 9_29 in the lung, liver, spleen, and kidneys was appreciably lower compared with [99mTc]Tc(CO)3-DARPin 9_29, which resulted in significantly (p < 0.05) higher tumor-to-organ ratios. The biodistribution data were confirmed by SPECT/CT imaging. In conclusion, radioiodine is a preferable label for DARPin 9_29.

To elaborate a high-performance system for expression of genes of G-protein coupled receptors (GPCR), methods of direct and hybrid expression of 17 GPCR genes in Escherichia coli and selection of strains and bacteria cultivation conditions were investigated. It was established that expression of most of the target GPCR fused with the N-terminal fragment of OmpF or Mistic using media for autoinduction provides high output (up to 50 mg/liter).

We present the spatial structure of binase, a small extracellular ribonuclease, derived from I H-NMR* data in aqueous solution. The total of 20 structures were obtained via torsion angle dynamics using DYANA program with experimental NOE and hydrogen bond distance constraints and P P and M M I dihedral angle constraints. The final structures were energy minimised with ECEPP/2 potential in FANTOM program. Binase consists of three K K-helices in N-terminal part (residues 61 6, 26^32 and 41^44), five-stranded antiparallel L L-sheet in Cterminal part (residues 51^55, 70^75, 86^90, 94^99 and 1041 08) and two-stranded parallel L L-sheet (residues 22^24 and 495 1). Three loops (residues 36^39, 56^67 and 76^83), which play significant role in biological functioning of binase, are flexible in solution. The differences between binase and barnase spatial structures in solution explain the differences in thermostability of binase, barnase and their hybrids.z 1998 Federation of European Biochemical Societies.

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The zinc(II)-binding affinities of recombinant human growth hormone and two its mutants, 14-33 and 14-95, were studied using Immobilized Metal Ion Affinity Gel-electrophoresis (IMAG). The mutant hormones, composed of polypeptide chain segments of the human and porcine growth hormones, lacked His18, which may be crucial for binding of the intact hormone to the transition metal ions. The mutations did not affect the affinity of human growth hormone to immobilized zinc ions; the structural analysis implied that the human growth hormone contains two IDA-Zn(II) potential sorption sites formed by amino acid residues His21, Asp171, and Glu174 and/or His18 and Glu174.