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Biomedical subjects

L Serrano

Publications and source records attributed to L Serrano.

At least 181 records · Page 10Linked to original sources
PubMed1986

Location of the regions recognized by five commercial antibodies on the tubulin molecule.

Through limited proteolysis of the tubulin molecule with trypsin, chymotrypsin, subtilisin, or pronase we have mapped the regions recognized by five commercial antibodies. Two of them recognized a sequence between amino acids 340 and 400 near the C terminal of the alpha or beta subunits, one recognized a sequence between amino acids 120 and 150 present in both subunits, and another one probably recognized a conformational epitope. Simultaneously we have confirmed the results obtained for other antibodies which recognized a region previously mapped on the tubulin molecule.

Amino Acid Sequence↗
PubMed1986

The removal of the carboxy-terminal region of tubulin favors its vinblastine-induced aggregation into spiral-like structures.

Vinblastine induces brain tubulin to assemble into spirals. This process is stimulated by microtubule-associated proteins (MAPs) which copolymerize with brain microtubules assembled in vitro. When the carboxy terminal of tubulin is removed by subtilisin digestion, vinblastine readily induces the aggregation of tubulin into spiral-like or circular structures, even in the absence of MAPs. These results suggest that in the absence of MAPs, the carboxy-terminal domain of tubulin may inhibit vinblastine-induced polymerization of tubulin into spiral-like structures.

Biopolymers↗
PubMed1986

The combined use of limited proteolysis and differential peptide staining for protein characterization.

A method to characterize a protein by peptide mapping is described. It involves a combination of limited proteolysis and differential staining with the dye 'stains all' which allows the identification of the proteolytic fragments by their size and colour. When this procedure was used for tubulin, specific acidic fragments were identified and localized in the molecule.

Electrophoresis, Polyacrylamide Gel↗
PubMed1986

Analysis of drug-tubulin interaction by trypsin cleavage: comparison for colchicine, podophyllotoxin, griseofulvin, vinblastine and taxol.

Trypsin preferentially cleaves the alpha subunit of depolymerized tubulin or vinblastine induced aggregates (in which longitudinal interactions between tubulin molecules could take place). No cleavage was found for tubulin polymerized into microtubules (containing lateral and longitudinal tubulin interactions), in the presence of taxol. In the presence of colchicine or podophyllotoxin the alpha subunit was partially protected from proteolytic digestion. Trypsin digestion pattern varied upon the addition of different concentrations of griseofulvin. At the higher concentration used, in which microtubules assembly was inhibited, both tubulin subunits were cleaved.

Alkaloids↗
PubMed1985

Localization of the tubulin binding site for tau protein.

Limited proteolysis of tubulin with subtilisin resulted in the removal of the carboxyl-terminal moiety of tubulin subunits. The remaining peptides from both alpha and beta tubulin lacking the carboxyl terminal did not bind to tau factor nor to MAP2 or MAP1. The carboxyl-terminal fragments bind to tau factor and MAP2 and both compete for the same binding sites in the tubulin molecule. Our results suggest that the carboxyl-terminal region of tubulin is a regulatory domain for the assembly of tubulin and the site for interaction with MAPs.

Animals↗
PubMed1985

The interaction between subunits in the tubulin dimer.

Limited proteolysis and chemical cross-linking techniques have been used to study the interaction between alpha- and beta-tubulin subunits. Trypsin digestion of tubulin dimer resulted in the cleavage of the alpha-subunit into two fragments, whereas chymotrypsin cleaved the beta-subunit into two distinct fragments. All of these fragments have been mapped on the tubulin subunits by further proteolysis with formic acid. Cross-linking of trypsin- and chymotrypsin-cleaved subunits has been performed with two different cross-linker agents of different cross-linking distance. The addition of formaldehyde resulted in the cross-linking of the alpha-tubulin N-terminal fragment with beta-tubulin C-terminal domain. The same result was obtained when methyl 4-mercaptobutyrimidate was used.

Animals↗
PubMed1984

Controlled proteolysis of tubulin by subtilisin: localization of the site for MAP2 interaction.

The treatment of tubulin with subtilisin resulted in a significant decrease in the ability of tubulin to assemble. The addition of taxol reduced the effect of subtilisin on the assembly of digested protein. Limited proteolysis of tubulin by subtilisin affected simultaneously both alpha- and beta-subunits, and it resulted in the appearance of two major cleavage fragments (32 and 20 kilodaltons) or an alternative pattern yielding two fragments (48 and 4 kilodaltons). The smallest peptide (4 kilodaltons) and also the 20-kilodalton fragment are localized in the C-terminal region of the tubulin alpha-subunit. Digested tubulin can assemble into sheet-shaped polymers, which cannot incorporate MAP2. On the other hand, the isolated C-terminal fragments can bind to MAP2. These results suggest that the carboxyl-terminal domain of the tubulin molecule is the site for the MAP2 interaction.

Animals↗
PubMed1984

Limited proteolysis of tubulin and the localization of the binding site for colchicine.

Limited proteolysis of porcine brain tubulin with trypsin resulted in a gradual loss of its colchicine binding activity as well as its ability of assembly into microtubules. The analysis of the tryptic degradation products showed a preferential proteolysis of alpha-tubulin subunit. This enzymatic proteolysis cleaved tubulin in one major site producing fragments of 36,000 and 16,000 daltons, the smaller polypeptides containing the carboxyl-terminal residue as shown by 14C tyrosination . However, proteolysis after incubation with 1 X 10(-3) M colchicine resulted in formation of the indicated fragments plus a 41,000-dalton fragment and smaller size peptides indicating the drug induces a second cleavage site closer to the carboxyl-terminal alpha-tubulin. Preincubation of tubulin with [3H]colchicine followed by proteolysis and separation of the fragments by Sephadex G-75 chromatography showed radioactive colchicine associated with the 16,000-dalton fragment and to the smaller size peptides resulting from digestion in the presence of the drug. The data indicate a localization of the colchicine-binding site in the 16,000-dalton segment containing the COOH-terminal region of alpha-tubulin subunit.

Animals↗
PubMed1984

Involvement of the carboxyl-terminal domain of tubulin in the regulation of its assembly.

Limited proteolysis of phosphocellulose-purified tubulin with subtilisin resulted in cleavage of both alpha and beta tubulin subunits, with the formation of two major fragments (S alpha, and S beta, 48 kDa) and a small peptide (4 kDa) containing the carboxyl-terminal region of tubulin. Interestingly, tubulin cleaved under the present conditions showed an increased ability to assemble into large polymers in the absence of MAPs and under conditions that do not promote assembly of undigested tubulin--i.e., low magnesium concentrations and the absence of taxol and polyalcohols. The critical concentrations for the subtilisin-cleaved tubulin assembly was similar to that of MAPs-promoted tubulin assembly. Assembly product from subtilisin-cleaved tubulin consisted mainly of protofilament bundles, hooked polymer, and open tubules, structures showing equatorial and longitudinal spacings of 50 and 40 A, respectively. The existence of junctions between polymer walls indicates that the carboxyl-terminal removal facilitates polymer-polymer interactions. These results, together with previous studies on the involvement of the carboxyl-terminal domain of tubulin in its interaction with MAP-2, suggest a regulatory role for this domain in tubulin assembly. Thus, in general terms the tubulin molecule can be analyzed as a protein containing two essential domains with functional significance, one domain playing a major role in self-association and the other (the carboxyl-terminal moiety) playing a regulatory role in modulating the interactions responsible for self-association.

Animals↗
PubMed1981

[Rheumatic carditis and its future (author's transl)].

Authors report results of the study of a series of rheumatic heart disease in 34 children between three and 14 years old, followed-up from one month to 14 years (mean six years and six months), and another one of 14 adults operated because of cardiac sequelae, in whom the average age was 48. The most significant results are: more common in autumn-winter (62%) and females (60%); family history of rheumatic fever (55%); low social level; mitral predominance with mitral regurgitation in children and stenosis in adults; during puberty age; without symptoms in the joints in 36%, and with better prognosis since 1974. Parameters with prognostic value in the prediction of sequelae were: family history of rheumatic fever; rural environment; increase in cardiac volume, PR prolongation in the ECG and inadequate treatment and prophylaxis. 36% of the mitral lesions and 20% of the aortic ones disappeared. The main conclusion is the need for intensive treatment during the acute period of the disease and continuous prevention during the rest of their lives of cardiac sequelae.

Adolescent↗
PubMed1976

Effects of azaperone on cardiovascular and respiratory functions in the horse.

1 The butyrophenone tranquilizer, azaperone, was administered intramuscularly, at dose levels of 0.4 and 0.8 mg/kg, to ponies and its effects on cardiovascular and respiratory functions assessed. 2 Arterial blood pH, CO2 tension (PaCO2) and O2 tension (PaO2) remained relatively constant throughout the course of action of azaperone. 3 Azaperone did not modify plasma protein concentration but venous blood packed cell volume and haemoglobin concentration were reduced by 5 to 10% for at least 4 hours. These changes were probably caused by uptake of erythrocytes into the splenic reservoir. 4 Small increases in heart rate occurred for up to 60 min after administration of the drug, and this was followed by a slight bradycardia in some ponies. 5 Azaperone reduced mean arterial blood pressure (MAP) for at least 4 h, by which time its ataractic action was generally no longer apparent. The hypotension was caused, during the early phase of action at least, by a reduction in peripheral resistance, since cardiac output was increased slightly 20 min after its administration. Possible mechanisms underlying the cardiovascular changes are discussed. 6 In spite of reductions in arterial blood O2 content and MAP produced by azaperone, it is likely that tissue oxygenation was adequate, since arterial blood lactate concentrations were not increased.

Animals↗
PubMed1976

The applied pharmacology of azaperone in ponies.

The butyrophenone tranquilliser, azaperone, was administered intramuscularly to ponies in five series of experiments, using a dose level of 0-4 mg/kg once and 0-8 mg/kg four times. An excellent or good sedative effect was usually obtained with both dose levels, but the response was more consistent with the higher dose. The onset of sedation was apparent within 10 min of administration, the maximal effect usually occurring between 20 and 60 min while sedation was no longer apparent after 2 to 6 h. Body temperature was reduced in all animals for at least 2 h and respiratory rate was increased in some ponies but not in others. A mild tachycardia occurred in the first hour after administering azaperone (0-8 mg/kg) and arterial blood pressure was reduced for at least 4 h. The hypothesis that azaperone reduced blood pressure by blocking alpha-adrenoceptors, thereby decreasing vasomotor tone, was tested by measuring the ability of azaperone (0-8 mg/kg) to antagonise the action of standard intravenous doses of adrenaline (1-5 mug/kg) on blood pressure, Azaperone partially antagonised the pressor action of adrenaline and in comparative studies the phenothiazine tranquilliser, acepromazine (0-1 mg/kg), also exerted a similar blocking effect.

Acepromazine↗