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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sedimentation analysis in the analytical ultracentrifuge has been used to characterize the size and shape of thermolysin and a number of its fragments obtained by chemical or enzymatic cleavage of the protein. Four fragments (121-316, 206-316, 225/226-316 and 255-316) originate from the C-terminal domain, and two (1-155 and 1-205) from the N-terminal domain of the intact molecule. In aqueous solution at neutral pH the hydrodynamic properties of the C-terminal fragments, except 255-316, are consistent with compact homogeneous monomers. Fragment 255-316 is a monomeric species below 0.08 mg/ml concentration and forms a dimer above this concentration. Dimerization does not lead to changes in fragment conformation, as determined by far-ultraviolet circular dichroic measurements, but to an increase of 5.6 degrees C (to 68.2 degrees C at 1.0 mg/ml) in the temperature for thermal unfolding and a corresponding increase of 4.6 kJ/mol in the free energy of unfolding. Fragments derived from the N-terminal domain show a strong tendency to form high-molecular-mass aggregates. Previous experiments utilizing circular dichroic measurements and antibody binding data suggested that the C-terminal fragments listed above are able to refold in aqueous solution at neutral pH into a stable conformation of native-like characteristics [Dalzoppo, D., Vita, C. & Fontana, A. (1985) J. Mol. Biol. 182, 331-340] (and references cited therein). Present data establish that all these C-terminal fragments are globular monomeric species in solution (at concentrations approximately 0.1 mg/ml) and thus represent 'isolated' domains (or subdomains) with intrinsic conformational stability typical of small globular proteins.
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PMID:Folding of thermolysin fragments. Hydrodynamic properties of isolated domains and subdomains. 277 48

The nucleotide sequence of two cloned fragments of human alphoid DNA was established. These fragments were earlier characterized in our laboratory as molecular markers of the 3rd (pHS05) and 11th (pHS53) chromosomes. Fragment pHS53 (2546 bp) contains alphoid repeats tandemly arranged and organized into three highly homologous pentamers. The heterogeneity of monomeric sequences within individual pentamers reaches 24-33%. Structural analysis of EcoRI subfragment pHS05 showed that this alphoid tetramer consists of two dimers 340 bp long. These dimers differ up to 16% from each other and from the so-called consensus sequence of the EcoRI-340 bp-restriction fragments family reported earlier by Wu and Manuelidis. The primary structure of four cloned fragments of EcoRI-340 bp-family was established. The data show that human alphoid DNA is highly heterogeneous. This conclusion is opposite to the view suggesting that alphoid DNA is a highly homogeneous class of reiterated sequences of the human genome.
Mol Biol (Mosk)
PMID:[Structural analysis of alphoid DNA of primates. I. Heterogeneity of nucleotide sequence of alphoid repeats in human DNA]. 301 12

Myosin heavy chain degradation fragments produced in vivo have been identified in chicken pectoralis muscle. The fragments were identified by electrophoresis of unfractionated extracts of chicken pectoralis muscle on sodium dodecyl sulfate/polyacrylamide gels followed by immunoblotting on nitrocellulose sheets. Monoclonal antibodies directed against the S2 and light meromyosin subfragments as well as type II myosin-specific polyclonal antibodies directed against the entire myosin heavy chain were used to characterize the fragments, which range in molecular weight from approximately 80,000 to 180,000. All fragments contain the extreme carboxy-terminal portion of the molecule and are distinct from the classical proteolytic fragments such as heavy and light meromyosin, S1, S2 or rod. These fragments appear to be produced in vivo by proteolytic cleavage of peptides from the amino-terminal (S1) end of the heavy chain while the myosin molecule is still embedded in the thick filament. Fragment concentrations are estimated to be approximately 5 to 10% of that of the intact myosin heavy chain. These fragments are not the result of artifactual damage to myosin, e.g. proteolysis or hydrodynamic shear. The techniques described in this paper provide a probe into the early stages of myosin and thick filament degradation in vivo.
J Mol Biol 1987 Jan 05
PMID:Myosin degradation fragments in skeletal muscle. 329 57

Imino proton exchange has been examined by NMR in the 5S RNA of Escherichia coli, its principal RNase A resistant fragment, fragment 1 (bases 1-11, 69-120), and complexes between that fragment and ribosomal protein L25 by using both real-time and relaxation techniques. Fragment 1 RNA imino protons exchange at rates between 0.5 and 15 s-1 at 303 K in 5 mM cacodylate buffer, pH 7.4. In contrast with many tRNAs, intact 5S RNA contains no imino protons with exchange lifetimes as great as 1 min. Consistent with the results of Gueron and his colleagues [Leroy, J. L., Bolo, N., Figueroa, N., Plateau, P., & Gueron, M. (1985) J. Biomol. Struct. Dyn. 2,915-939; Leroy, J. L., Broseta, D., & Gueron, M. (1985) J. Mol. Biol. 184, 165-178] with tRNA, exchange in 5S RNA is catalyst-limited under conditions generally used for imino proton spectroscopy, such as those given above. Using Gueron's catalyst saturation technique, base pair opening rates have been measured for several AU and GU base pairs in fragment 1. They range from 50 to 300 s-1 at 303 K and depend on base pair type and also to some degree on context. Similar studies have been done on complexes of L25 and fragment 1. The binding of L25 to fragment 1 reduces the exchange rate of many imino protons within the region to which it binds, consistent with the hypothesis that its binding stabilizes the secondary structure of 5S RNA.
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PMID:Imino proton exchange in the 5S RNA of Escherichia coli and its complex with protein L25 at 490 MHz. 353 86

Plasmid pRP761 is a derivative of the promiscuous plasmid RP4, which has a Tn76 insert 1.8 kb from its EcoRI site within the trfB region (Barth 1979). This mutation was pleiotropic, having three effects: the plasmid is unstably maintained in E. coli, it reduces the growth rate of its host and it has suffered a reduction in host-range. We show that pRP761 has reduced expression from both its korA and korB genes and that Tn76 has inserted between them. Fragment exchange experiments showed that this is the only mutant region in pRP761 and is therefore solely responsible for the pleiotropic effects. A spontaneous deletion derivative pRP761-6 has lost Tn76 and its adjacent kilA and korA genes: it has reacquired stability, does not inhibit host growth but is still reduced in its host-range. The provision of cloned korA+ in trans complements the first two phenotypic effects in pRP761 to a large extent, but neither korA+ alone nor korA+ with korB+ complements the host-range reduction in pRP761 or pRP761-6. A possible explanation for these results is that there is a site between korA and korB, affected by the Tn76 insert, that is essential to stable replication of these plasmids in some of their bacterial hosts.
Mol Gen Genet 1984
PMID:Involvement of kil and kor genes in the phenotype of a host-range mutant of RP4. 609 93

Specific antibody to a fragment [CBb(2-56)] of porcine muscle adenylate kinase was purified from goat antiserum against adenylate kinase on an immunoadsorbent column. This anti-CBb antibody cross-reacted in solid phase radioimmunoassay with two other CNBr-fragments of adenylate kinase, CBfN(81-125) and CBfC(126-194). This cross-reactivity explained their high inhibition activities in quantitative precipitin reaction between adenylate kinase and goat antiserum shown in the previous work. Cysteinyl residues of the enzyme (positions 25 and 187) were S-cyanylated with 2-nitro-5-thiocyanobenzoic acid and the enzyme was cleaved at these residues. Fragment 1-24 thus obtained was purified. The fragment 1-24, composing the N-terminal half of CBb(2-56), accounted for full activity of CBb to anti-CBb in radioimmunoassay. Hence antigenic region(s) of CBb(2-56) exist in its N-terminal half, 2-24, and this determinant(s) may be closely related to the cross-reactivity among CB-fragments. CBfN also bound to the antibody fraction which had not been adsorbed to CBb-Sepharose (non-anti-CBb). CBfN carried additional antigenic regions. In conclusion, we propose that the antigenic reactive region(s) of adenylate kinase responsible for the cross-reactivity of the CB-fragments are as follows: -Glu-Glu-Lys-Leu-Lys-Lys- (2-7), -Glu-Glu-Phe-Lys-Arg-Lys- (103-108), -Glu-Glu-Thr-Ile-Lys-Lys- (143-148).
Mol Immunol 1983 Aug
PMID:Antigenic structure of adenylate kinase from porcine skeletal muscle--II. Immunochemical cross-reactivity of fragments from adenylate kinase. 619 28

The DNA of the recombinant phage lambda gtWES Mr974 (GRUMMT et al., 1979) which contains the 18S region and adjacent spacer sequences of the ribosomal genes from mouse has been digested with the restriction endonuclease SalI. Fragments corresponding to the non-transcribed spacer (A and D) and the external transcribed spacer (B) have been prepared and their nucleotide composition and sequence organization has been determined. The data indicate that the part of the non-transcribed spacer contained in Mr974 consists of at least two structural domains of distinct sequence characteristics. Fragment A contains 49% G + C and exhibits a high sequence complexity. Fragment D, the spacer fragment flanking the coding region, is very rich in G + C and is obviously composed of an internally repetitive sequence which is cut by several restriction enzymes into a similar set of repetitive fragments. Most of the fragments have sizes that are multiples of 60 and 80 or 140 base pairs, respectively, suggesting an alternating 60/80bp arrangement. This regular sequence in fragment D accounts both for the observed instability and length heterogeneity of the rDNA insert in several clones and probably for the heterogeneity in the structure of the ribosomal repeats in the genomic DNA.
Mol Gen Genet 1980 Jan
PMID:Structural organization of mouse rDNA: comparison of transcribed and non-transcribed regions. 624 36

The structure and activities of the recombination-promoting P22 Erf protein were examined in vitro. Treatment of the protein with elastase produces a stable amino-terminal fragment, consisting of amino acid residues 1 to (approximately) 136. We have purified this fragment, designated fragment B, to apparent homogeneity by gel filtration chromatography. Fragment B retains the oligomeric structure and single-stranded DNA binding specificity of intact Erf. It differs, however, in lacking the ability of intact Erf to bind single-stranded DNA into large aggregates following mild heat treatment of the protein. In addition, its binding to DNA may be weaker than that of intact Erf. Intact Erf sediments through a sucrose gradient as a discrete species with an apparent S20,w of approximately 11 X 7 S. Its sedimentation behavior is affected little, if at all, by concentration. Fragment B also sediments as a discrete species at approximately 10 X 4 S. In the electron microscope, intact Erf appears as rings, with 10 to 14 small projecting structures resembling the teeth of a gear. Fragment B is similar, except that it appears to lack the peripheral structures. From these observations, we conclude that Erf consists of at least two structurally and functionally distinct domains, and that it has a discrete ring-like oligomeric structure.
J Mol Biol 1983 Dec 25
PMID:Domain structure and quaternary organization of the bacteriophage P22 Erf protein. 660 60

Escherichia coli ribosomal protein S1 and its mutant, shorter, form m1-S1 were cleaved at internal methionyl residues to yield, respectively, six and five fragments of Mr ranging from 1000 to 24000. Methods are described to isolate the fragments in pure form. Four of the fragments (designated F2a, F2b, F3 and F4) contain between 86 and 215 amino acids and are therefore as large as other ribosomal proteins. Fragment F2a, derived from the N-terminal region, has previously been shown to contain the major ribosome binding domain of S1 [S. Giorginis and A. R. Subramanian (1980) J. Mol. Biol. 141, 393--408]. Here we show that the RNA binding domain of S1 is essentially contained in F3 derived from the middle region of S1 and carrying the nonreactive--SH group. The reactive--SH group of S1, whose activity is modified by ligand binding, was localized in F2b, a fragment with little RNA binding capacity. The characteristic RNA binding domain and a weak ribosome binding domain of S1 have previously been localized in the large trypsin-resistent core S1-F1 [T. Suryanarayana and A. R. Subramanian (1979) J. Mol. Biol. 127, 41--54]. Together these data indicate that two of the key functional domain of S1 are located in two regions of the molecule separated by an open, exposed segment. The present study also revealed that the nonreactive--SH group of S1 becomes reactive in m1-S1 by the loss of the remote C-terminal region in the latter.
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PMID:Fragments of ribosomal protein S1 and its mutant form m1-S1. Localization of nucleic-acid-binding domain in the middle region of S1. 703 Jul 33

The binding of rabbit skeletal muscle troponin-T and several of its fragments to various types of tropomyosin immobilized on Sepharose 4B affinity columns equilibrated with 0.1 M NaCl, pH 7.0 buffer has been investigated. With rabbit skeletal muscle alpha-tropomyosin, intact troponin-T was eluted with an NaCl gradient at 0.42 M, while its fragments T1 (residues 1-158) and CB1 (residues 1-151) were eluted at 0.32 M NaCl in either "plus" or "minus" Ca2+ buffer in the presence of troponin-C. Fragment T2 (residues 159-259) was eluted at 0.22 M NaCl in minus Ca2+ buffer in the presence of troponin-C, but in the void volume with troponin-C under plus Ca2+ conditions. With immobilized nonpolymerizable alpha-tropomyosin, T1 was not bound, whereas T2 was eluted at the same NaCl concentration (0.21 M) as with alpha-tropomyosin. This binding was sensitive to Ca2+ in the presence of troponin-C. The results are consistent with a structural interpretation of a two-site model of troponin attachment to alpha-tropomyosin (Mak, A. S., and Smillie, L. B. (1981) J. Mol. Biol. 149, 541-550). With beta-tropomyosin from rabbit skeletal muscle and with tropomyosins from equine platelets and chicken gizzard, the binding of fragment T1 was not observed at 0.1 M NaCl, while that for T2 was the same as for rabbit skeletal alpha-tropomyosin and remained Ca2+-sensitive in the presence of troponin-C. In the case of bovine aorta tropomyosin, neither T1 nor T2 was bound under these conditions.
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PMID:Binding of troponin-T fragments to several types of tropomyosin. Sensitivity to Ca2+ in the presence of troponin-C. 710 28


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