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Biomedical subjects

G Amiconi

Publications and source records attributed to G Amiconi.

123 records · Page 7Linked to original sources
PubMedDate not supplied

Binding of the soybean Bowman-Birk proteinase inhibitor and of its chymotrypsin and trypsin inhibiting fragments to bovine alpha-chymotrypsin and bovine beta-trypsin. A thermodynamic study.

The effect of pH and temperature on the apparent association equilibrium constant (Ka) for the binding of the soybean Bowman-Birk proteinase inhibitor (BBI) and of its chymotrypsin and trypsin inhibiting fragments (F-C(p), F-T(p) and F-T(t), respectively) to bovine alpha-chymotrypsin (alpha-chymotrypsin) and bovine beta-trypsin (beta-trypsin) has been investigated. On the basis of Ka values, the proteinase inhibitor affinity can be arranged as follows: alpha-chymotrypsin: BBI approximately beta-trypsin:BBI approximately beta-trypsin:F-T(t) approximately beta-trypsin:F-T(p) much greater than alpha-chymotrypsin:F-C(p). F-C(p), F-T(p) and F-T(t) do not inhibit beta-trypsin and alpha-chymotrypsin action, respectively. On lowering the pH from 9.5 to 4.5, values of Ka for BBI, F-C(p), F-T(p) and/or F-T(t) binding to alpha-chymotrypsin and beta-trypsin decrease, thus reflecting the acid-pK shift of the invariant His57 catalytic residue from 7.0, in the free enzymes, to 5.2, in the proteinase:inhibitor complexes. Considering the known molecular models, the observed binding behaviour of BBI, F-C(p), F-T(p) and F-T(t) was related to the inferred stereochemistry of the proteinase:inhibitor contact regions.

Animals↗
PubMedDate not supplied

Binding of the recombinant proteinase inhibitor eglin c from leech Hirudo medicinalis to serine (pro)enzymes: a comparative thermodynamic study.

The binding of the recombinant proteinase inhibitor eglin c from the leech Hirudo medicinalis to serine (pro)enzymes belonging to the chymotrypsin and subtilisin families has been investigated from the thermodynamic viewpoint, between pH 4.5 and 9.5 and from 10 degrees C to 40 degrees C. The affinity of eglin c for the serine (pro)enzymes considered shows the following trend: Leu-proteinase [the leucine specific serine proteinase from spinach (Spinacia oleracea L.) leaves] greater than human leucocyte elastase congruent to human cathepsin G congruent to subtilisin Carlsberg congruent to bovine alpha-chymotrypsin greater than bovine alpha-chymotrypsinogen A congruent to porcine pancreatic elastase congruent to bovine beta-trypsin. The serine (pro)enzyme-inhibitor complex formation is an entropy-driven process. On increasing the pH from 4.5 to 9.5, the affinity of eglin c for the serine (pro)enzymes considered increases thus reflecting the acid pK shift of the invariant hystidyl catalytic residue from approximately to 6.9 in the free serine proteinases and bovine alpha-chymotrypsinogen A to congruent to 5.1 in the serine (pro)enzyme-inhibitor complexes. Considering the known molecular models, the observed binding behaviour of eglin c was related to the inferred stereochemistry of the serine (pro)enzyme-inhibitor contact regions.

Animals↗
PubMedDate not supplied

Reinfection of Somali children with Trichuris trichiura after chemotherapy: relevance of immunostimulation.

The intestinal helminth status of an age-stratified sample (6 to 20 years old) from a Somalian community has been assessed and the typical pattern of highly aggregated parasite distribution found. A reinfection study on a sample of 40 children (treated and untreated with a pentapeptide identical to the active site of the thymic hormone thymopoietin) seemed to indicate that immunological factors play a significant role in modulating the population dynamics of infection in endemic communities.

Adolescent↗
PubMedDate not supplied

An epidemic of Neisseria gonorrhoeae in a Somali orphanage.

Neisseria gonorrhoeae was isolated from 53 young females (6-14 years old) in a Somali orphanage. A male guardian was found to be the effective transmitter having sexually abused the children. All the bacterial isolates were of the same serogroup WI and the same serovar Aedih. This presents an unusual example of a tight geographic cluster of infected people which is often characteristic of gonorrhoea epidemics.

Adolescent↗
PubMedDate not supplied

[Hirudin inhibition of human thrombin activity].

Thermodynamics and kinetics for hirudin binding to human alpha-, beta- and gamma-thrombin, under experimental conditions which mimic the in vivo conditions (i.e., pH = 7.35, T = 37.0 degrees C, I = 0.1 M), indicate that the inhibitor specificity for the three species of the enzyme is different. Such a finding agrees with the human thrombin:hirudin binding geometry as revealed by X-ray crystal studies. From the therapeutic viewpoint, thermodynamics and kinetics here reported indicate that the inhibitory activity of hirudin in vivo is more effective than that shown by antithrombin III, which is generally considered the most important plasma thrombin inhibitor.

Hirudins↗