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At least 883 records · Page 49Linked to original sources
PubMed1981

A new heterobifunctional cross-linking reagent for the study of biological interactions between proteins. II. Application to the troponin C-troponin I interaction.

A simple chromatographic procedure using DEAE-Sephadex has been established to isolate the troponin I-troponin C complex from unbound troponin I (TnI) and troponin C (TnC). A 1:1 complex can be formed between bovine cardiac carboxamidomethylated troponin I and rabbit skeletal troponin C. The formation of the complex is calcium dependent. It is stable to DEAE-chromatography in 6 M urea, 3 mM Ca2+ and can be dissociated on DEAE-chromatography in the presence of 6 M urea, 1 mM ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. TnC was modified with the photoaffinity probe AGTC (N-(4-azidobenzoyl-[2-3H]glycyl)-S-(2-thiopyridyl)-cysteine) at its single cysteine residue (position 98). Photolysis of the CM (carboxamidomethylated)-TnI-AGC-TnC complex resulted in the formation of a covalently linked 1:1 complex. The isolated covalently linked complex could be treated with dithiothreitol to reduce the disulfide bond between N-(4-azidobenzoyl-[2-3H]glycyl)-cysteine (AGC) and TnC to complete the transfer of the radiolabeled AGC from cysteine 98 on TnC to CM-TnI. The CM-TnI-AGC was isolated from TnC on DEAE-chromatography in 6 M urea, 1 mM EGTA, 1 mM dithiothreitol buffer. The formation of the covalent bond between the photoaffinity probe and TnI indicates the close proximity of TnI to cysteine 98 on the TnC. These results demonstrate the general utility of the new heterobifunctional cross-linking reagent to study protein interactions.

Affinity Labels↗
PubMedDate not supplied

[Electronic-conformational interactions of molecular-biological systems. I. Quantum-chemical aspect of the theory of electronic-conformational interaction].

Electronic-conformational interactions (ECI) are the main causes of enzymatic catalysis and other biological processes, occuring at the molecular and super-molecular levels. For the studies of several problems, related to ECI the qualitative methods of quantum chemistry can be used, in particular the method of intermolecular orbitals. The possibilities of this method are shown in some simple cases.

Biopolymers↗
PubMed1994

Social interaction and symptom sequences: a case study of orofacial bradykinesia exacerbation in Parkinson's disease during negative marital interaction.

Evidence is rapidly accumulating that disease symptoms are influenced by psychological factors, and most potently, by familial relationships. This case study demonstrated the detrimental influence of negative marital interaction on orofacial bradykinesia and speech productivity in a 74 year old male Parkinson's disease patient. An increase in bradykinesia symptoms followed a series of specific negative comments by the wife during a conversation; these symptoms showed partial reversal during a subsequent conversation with a lab assistant. The analytic method and data summary strategies used to determine this relationship are discussed relative to their possible utility for other disorders.

Aged↗
PubMedDate not supplied

[Electrostatic interaction and differences in specific and nonspecific interactions of the Lac-repressor with DNA].

To investigate the complexes of lac-repressor with specific and non-specific DNA sequences method of covalent cross-linking of proteins to partially depurinated DNA was used. We have identified the amino acid resides which form cross-links and hence are proximate to DNA. Only lysine 33 is cross-linkable in specific complex. In the case of non-specific complex (at the presents of inducer molecules) lysine 33 remains cross-linkable. Some consequences of these phenomena in aspects of the physical backgrounds of protein-DNA interactions have been discussed.

Amino Acid Sequence↗
PubMed1993

In vivo DNA-protein interactions at the divergent mercury resistance (mer) promoters. II. Repressor/activator (MerR)-RNA polymerase interaction with merOP mutants.

Transcription of the Tn21 mercury resistance (mer) operon is regulated by MerR which represses and activates the mer structural genes (merTPCAD) in the absence and presence of Hg(II), respectively. The promoter for the structural genes (PTPCAD) is divergently overlapped with the promoter for the regulatory gene (PR), and a dyadic operator lies between the -10 and -35 hexamers of PTPCAD. Using in vivo dimethyl sulfate and KMnO4 footprinting of mutant mer operator-promoter (merOP) DNA to observe MerR and RNA polymerase-mediated interactions with the merOP region, we have identified three distinct domains within the palindromic mer operator. Dyad domain I consists of the outermost bases on the left arm of the operator palindrome whose alteration causes a shift, but apparently not a major loss, in occupancy by MerR, and no decrease in RNA polymerase occupancy. Mutants in dyad domain I are semiconstitutive but support additional Hg(II)-induced open complex formation at PTPCAD. Dyad domain II consists of the four highly conserved inner bases ( ... GTAC ... GTAC ... ) of the seven-base interrupted dyad, alteration of which severely modifies both MerR and RNA polymerase contacts in the promoter region. Mutants in domain II generally allow constitutive open complex formation at PR. One unusual mutant of this group retains most of the wild-type dyad's ability to repress both promoters but is unable to support activation at PTPCAD in response to Hg(II), indicating that MerR undergoes a conformational change and that the required base contacts for activation are different than those for repression. Dyad domain III is tentatively defined by a mutant in the outermost base of the right palindrome arm which is unaffected in either MerR or RNA polymerase occupancy, however, a second lesion within the PTPCAD -10 hexamer of this mutant limits effective open complex formation. Other mutations lying solely within the -10 RNA polymerase recognition hexamer of PTPCAD are similarly competent in both MerR and RNA polymerase binding, but inadequate for open complex formation. One such mutant also affects the overlapping -10 hexamer of PR and results in reduced occupancy by both MerR and RNA polymerase, likely as a result of inefficient transcriptional initiation of merR mRNA. Finally, mutations affecting the -35 hexamer of PTPCAD bind MerR but not RNA polymerase.(ABSTRACT TRUNCATED AT 400 WORDS)

Bacterial Proteins↗
PubMed1997

[Comparison of film-screen combinations with contrast detail diagram and interactive image analysis. 2: Linear assessment of grey scale ranges with interactive image analysis].

The following three screen-film combinations were compared: a) a combination of anticrossover film and UV-light emitting screens, b) a combination of blue-light emitting screens and film, and c) a conventional green fluorescing screen-film combination. Radiographs of a specially designed plexiglass phantom (0.2 x 0.2 x 0.12 m3) with bar patterns of lead and plaster and of air, respectively were obtained using the following parameters: 12 pulse generator, 0.6 mm focus size, 4.7 mm aluminum pre-filter, a grid with 40 lines/cm (12:1) and a focus-detector distance of 1.15 m. Image analysis was performed using an IBAS system and a Zeiss Kontron computer. Display conditions were the following: display distance 0.12 m, a vario film objective 35/70 (Zeiss), a video camera tube with a PbO photocathode, 625 lines (Siemens Heimann), an IBAS image matrix of 512 x 512 pixels with a resolution of 7 lines/mm, the projected matrix area was 5000 microns2. Grey scale ranges were measured on a line perpendicular to the grouped bar patterns. The difference between the maximum and minimum density value served as signal. The spatial resolution of the detector system was measured when the signal value was three times higher than the standard deviation of the means of multiple density measurements. The results showed considerable advantages of the two new screen-film combinations as compared to the conventional screen-film combination. The result was contradictory to the findings with pure visual assessment of thresholds (part I) that had found no differences. The authors concluded that (automatic) interactive image analysis algorithms serve as an objective measure and are specifically advantageous when small differences in image quality are to be evaluated.

Algorithms↗
PubMed1999

Policy issues relevant to evaluation of interactive health communication applications. The Science Panel on Interactive Communication and Health.

This article provides an analysis of policy-related issues associated with the evaluation of interactive health communication (IHC) applications. These include an assessment of the current health and technology policy environment pertinent to public (government, education, public health) and private (medical care providers, purchasers, consumers, IHC developers) IHC stakeholders and discussion of issues likely to merit additional consideration by these stakeholders in the future.

Community Participation↗
PubMed1975

Amitriptyline-perphenazine interaction in ambulatory schizophrenic patients. A controled study of drug interaction.

In a double-blind placebo, controlled clinical study, lasting 12 weeks, 48 male and 48 female ambulatory schizophrenic patients were randomly assigned to one of four treatments: placebo; amitriptyline hydrochloride, 125 mg/day; perphenazine, 20 mg/day; or amitriptyline-perphenazine, 20 mg/day. Treatment groups contained an equal number of male and female patients. Perphenazine alone or in combination was substantially more effective in reducing psychopathological disorder than was the placebo, but there was no evidence to indicate the superiority of the amitriptyline-perphenazine combination over perphenazine alone. Amitriptyline alone was not substantially better than placebo and could not be considered an efficacious medication for the maintenance treatment of these patients. Less response to treatment was made by patients with longer-term records of prior hospitalization.

Adult↗