Physicochemical properties of a fibrinolytic enzyme from Streptomyces thermovulgaris culture broth

Some properties of fibrinolytic enzyme from cultural fluid of Streptomyces thermovulgaris have been studied. The molecule of enzyme has been shown to consist of one polypeptide chain with molecular mass 28000 dalton, pi = 7.45-7.6. The amino acid composition of protein is determined, the protein does not contain cysteine residues. The enzyme is not thermostable, and Ca2+ ion does not exert stabilized influence. In opposition to diisopropylfluorophosphate, phenylmethylsulfonyl fluoride does not inhibit the enzyme activity.     

Oligonucleotide labeling using BODIPY phosphoramidite

4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives were prepared and their photochemical properties were characterized. One such analogue, 4,4-difluoro-4-bora-1,3,5,7-tetramethyl-8-(5-hydroxypentyl)-3a,4a-diaza-s-indacene was transformed into the corresponding phosphoramidite and incorporated into oligodeoxyribonucleotides as a fluorescent reporter group.     

Fluorescently labeled differentiating myelopeptide-4: specific binding to and penetration into target cells

Myelopeptide-4 (MP-4) (Phe-Arg-Pro-Arg-Ile-Met-Thr-Pro), inducing the terminal differentiation of HL-60 leukemia cells, was labeled with fluorescein isothiocyanate. The specific binding of this modified peptide to the surface of HL-60 cells and its ability to penetrate into the cells were studied. It was shown by cytometry and confocal microscopy to be bound on the HL-60 cell surface, to penetrate into their cytoplasm, and finally to concentrate around the cell nucleus. These phenomena are probably necessary for the exhibition of MP-4 differentiating activity.     

A study of blood albumin of various animal species by the spectral luminescent method

The functional differences of blood serum albumin of some animal species have been studied using the spectral luminescent method by comparing the binding constants K and the concentration of binding sites N of rhodamine B and rhodanmine S to albumin. It was shown that K and N depend on both the concentration of blood serum albumin and animal species and the dye used.     

A study of annexin family protein in early development of fish. II. Analysis of complete amino acid sequence

We studied mRNA structure of 31 kDa annexin of zebra fish Brachydanio rerio using previously obtained 3'-terminal incomplete cDNA. The size of this protein mRNA was determined by Northern hybridization. PCR screening of cDNA library of zebra fish gastrula allowed us to obtain cDNA of the 5'-terminal regions of the mRNA. The primary structure of the protein deduced from the mRNA sequence allowed us to identify it as an annexin IV with threonine in position 6--a phosphorylation target for protein kinase C.     

Depolymerization of actin microfilaments in the I--Z--I brushes of transverse striated muscles by using DNAse I

To release Z-discs of skeletal muscles myofibrils from actin microfilaments, I--Z--I-brushes (complexes of Z-discs and thin filaments) were treated with DNAse I-both in suspension and on electron microscopical grids. It was shown that such a treatment resulted in depolymerization of actin filaments. The preparations obtained were heterogeneous and contained I--Z--I-brushes with shorter actin filaments and single Z-discs. The structure of Z-discs released from actin filament remained intact. Therefore these preparations may be used in studies on regulation of actin microfilaments assembly.     

Features of the structural organization of inactivated actin--an intermediate form of the protein during the folding-unfolding process

The structure of inactivated actin was studied by the methods of intrinsic fluorescence upon stationary and pulse excitation, selective fluorescence quenching with acrylamide, and testing the protein surface with a hydrophobic probe, 8-anilino-1-naphthalenesulfonic acid (ANS). The results are discussed along with earlier data on actin sedimentation, near- and far-UV CD spectra, and fluorescence anisotropy. The thermodynamic stability of inactivated actin, the presence of a secondary structure characteristic of the native protein, and the reversibility of the inactivated actin-completely unfolded actin transition allow inactivated actin to be considered an intermediate form in the process of protein folding into the native globular structure. In vitro actin inactivation is accompanied by specific association of actin macromolecules resulting in the formation of homogeneous stable complexes. The tendency toward aggregation (or specific association, in the case of actin), which is determined by the presence of extended hydrophobic clusters on the molecule surface, appears to be one of the intrinsic properties of any protein in the intermediate state. The mobility of the amino acid side chains in the inactivated actin differs considerably from that in the completely unfolded actin. The relaxation properties of the microenvironment of tryptophan residues determine relatively long-wave fluorescence spectra of the inactivated actin. However, the mobility observed is insufficient to compensate the asymmetry of the microenvironment of aromatic residues, which is confirmed by a characteristic and intense CD spectrum in the near-UV region. The mobility of the indole rings of tryptophans located in the internal regions of the inactivated actin that are solvent-inaccessible although polar is even considerably lower than that in the native actin.