13-Demethylbacteriorhodopsin: formation and some properties.

Incorporation of 9-cis-13-demethylretinal into bacterioopsin was shown to form the covalent purple complex. This result was predicted by our hypothesis about the structure of the BR chromophore cavity (Mol. Biologiya 29:1398-1407 (1995) (in Russian)). It supports the hypothesis and eliminates the main objection known from the literature.

Isolation of individual amino acids from various microbiological sources using reversed-phase high-performance liquid chromatography.

A new method for the preparative isolation of individual amino acids on a milligram scale based on reversed-phase high-performance liquid chromatography (RP-HPLC) after pre-column derivatization with carbobenzoxychloride (Z-Cl) has been developed. The chromatographic procedure was tested by the investigation of jack bean urease hydrolysate. The method has been applied to the preparative separation of Z-amino acids (from 10 up to 16) obtained from protein hydrolysates of various sources (green microalgae, blue-green algae, halophilic and methylotrophic microorganisms) and was proved to be reliable by the separation of deuterated amino acids (enrichment 97-99%) from Methylobacillus flagellatum (due to the bioconversion of CD3OD and D2O). Independent of the biological source of the protein, the amino acids were isolated with high recovery (from 68% up to 89%) and chromatographic purity (from 96% up to 99%). The method was also applied for the isolation of phenylalanine and leucine excreted by amino-acid overproducing microorganisms.

[Synthesis of the tripeptide glycyl-L-leucyl-L-phenylalanine and its analogs]. / Sintez tripeptida glitsil-L-leitsil-L-fenilalanina i ego analogov.

Peptide Gly-L-Leu-L-Phe and its derivatives were synthesized by the C-end elongation utilizing DCC/HOBT technique and by enzymatic route with the help of papain using esters of N-benzyloxycarbonyl-glycine and -L-leucine as acyl donors have been suggested. The chemical, similarly to the enzymatic, synthesis was not accompanied by racemization. Conditions for HPLC separation and preparative isolation of the enzymatic reaction products were developed.

C(13)-substituted bacteriorhodopsin analogs.

13-Ethyl-, 13-isopropyl-, 13-tert-butyl-, 13-phenyl-, 13-alpha-naphthyl-, and 13-demethyl-retinals were synthesized and incubated with bacterioopsin (bO) to give the corresponding bacteriorhodopsin (bR) analogs. The capability of the 13-tert-butyl- and 13-alpha-naphthyl-bRs to exist and to photocycle shows that apparently around C(13) of the chromophore there lies a large enough cavity. A study of the light-induced conversions of the artificial pigments prepared has shown that the introduction at position 13 of the chromophore of the hydrocarbon substituents bulkier than that of the natural bR diminished the amplitudes of the electric photoresponses. Bulky C(13)-substituents or absence of substitution at that position decelerated the relaxation of the M-intermediates and disturbed the 13-cis-in equilibrium all-trans-isomerization.

[Synthesis and properties of C13-substituted retinals]. / Sintez i svoistva C13-zameshchennykh retinalei.

Several analogues of all-trans-retinal were synthesised, containing, instead of CH3-group at C13, the following substituents: H, C[2H]3, C2H5, iso-C3H7, C4H9, C6H5 or alpha-C10H8. The compounds synthesised on coupling with bacterioopsin gave artificial chromoproteins, which retained the ability to participate in the cycle of photochemical transformations and H+-transport.