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Biomedical subjects

A Berti

Publications and source records attributed to A Berti.

85 records · Page 5Linked to original sources
PubMed1978

Stability of horse muscle acylphosphatase to heat and to urea.

The thermal stability of horse muscle acylphosphatase was investigated by measuring the inactivation constants at various pH and temperature values, and by differential spectra technique. This enzyme has high thermal stability in an acidic environment but is inactivated in an alkaline medium. It was found that the enzyme can be protected against such inactivation at pH 8.0 by increasing its concentration and the ionic strength of the solution. The effect of high urea concentrations on stability was also measured. It was found that spectral changes at 230 nm are related to urea inactivation of the enzyme, and that the enzymatic activity can be instantly and almost completely restored by dilution of the urea.

Acid Anhydride Hydrolases↗
PubMed1978

Stability and kinetic behavior of carboxymethylated horse muscle acylphosphatase.

Horse muscle acylphosphatase consists of a main chain S-S bound to glutathione. It was found that removal of the glutathione by reduction and successive carboxymethylation of the only cysteine of the main chain affects the stability of the enzyme, mainly with respect to thermal inactivation. On the other hand, the kinetic properties of the enzyme are affected very little.

Acid Anhydride Hydrolases↗
PubMed1976

[Possibilities in the field of craniofacial surgery].

Four cases which illustrate possibilities of a new field in craneofacial surgery are presented. Using certain surgical principles, various conditions whose previous treatment was unsastisfactory, can be corrected. Hope is thus given to many persons with severe facial deformities.

Adolescent↗
PubMedDate not supplied

Horse muscle acylphosphatase: a more rapid purification procedure and crystallization.

A crystalline acyl phosphatase has been obtained from horse muscle. The enzyme purified by a modified procedure which allowed to obtain a larger yield with respect to a method previously developped in this laboratory, was homogeneous by disc electrophoresis on polyacrylamide gel. Crystals of this enzymatic protein have been obtained by the addition of ammonium sulphate to around 52% saturation.

Acid Anhydride Hydrolases↗
PubMedDate not supplied

Horse heart acylphosphatase: purification and characterization.

The use of an affinity chromatography step performed with an immunoadsorbent consisting of anti-horse muscle acylphosphatase antibodies covalently linked to Sepharose 4B allowed us to purify horse heart acylphosphatase in a very rapid and efficient fashion. As in skeletal muscle, also in heart the enzyme is present as both a mixed disulfide with glutathione and a S-S dimer. The abundance of these forms in heart is quite lower than in skeletal muscle. The comparison of the molecular forms so purified with those obtained from horse skeletal muscle showed the same aminoacid composition, tryptic fingerprint, together with strictly similar apparent molecular weight and main kinetic parameters, supporting the conclusion that the acylphosphatase present in heart is the same enzyme as that purified from skeletal muscle.

Acid Anhydride Hydrolases↗
PubMedDate not supplied

The complete amino acid sequence of bovine skeletal muscle acylphosphatase.

The primary structure of bovine skeletal muscle acylphosphatase was determined by performing the sequence analyses of the complete series of tryptic peptides. The amino acid composition of the entire series of peptic peptides was used to reconstruct the sequence by the overlapping method. The proposed structure is further confirmed by analogy with known amino acid sequences of acylphosphatase from skeletal muscle of other vertebrate species. The length of the polypeptide chain is 98 residues, identical to the length of the enzymes from other known mammalian species, but different from that found in turkey. The enzyme is NH2-acetylated and a comparison with the analogous molecular forms from other vertebrate species indicates that there are several long polypeptide stretches strictly conserved (93-97% identical position among mammals, and about 80% between calf and turkey enzymes).

Acid Anhydride Hydrolases↗
PubMedDate not supplied

Quantitative determination of acylphosphatase levels in horse tissues by enzyme-linked immunosorbent assay.

A non competitive enzyme-linked immunosorbent assay (ELISA) specific for horse muscle acylphosphatase (E.C. 3.6.1.7.) has been developed. The purified anti-acylphosphatase antibodies were immobilized by passive absorption to a solid-phase support and incubated with known and unknown amounts of antigen. The antibody-acylphosphatase complex was quantified using the same antibody conjugated to horseradish peroxidase. The assay yields positive reactions with as little as 0.05 ng of antigen, with intra- and interassay coefficients of variation of 5% and 7%, respectively. On the basis of this assay we developed a more sensitive test than the optical one, using benzoyl-phosphate as substrate, for acylphosphatase determination. By means of this test, the presence of the enzyme in horse tissue homogenates was evaluated under conditions in which the optical test failed to distinguish the acylphosphatase activity from that of other enzymes.

Acid Anhydride Hydrolases↗
PubMedDate not supplied

Turkey muscle acylphosphatase: purification and comparative studies.

Turkey muscle acylphosphatase is strongly bound to anti-(horse muscle acylphosphatase ) antibodies covalently linked to an agarose resin. This permits use of an affinity chromatography step in the purification, which increased the final yield and allowed us to isolate three different molecular forms of the enzyme. Form 1 is a mixed disulfide between the polypeptide chain and glutathione; form 3 is an S-S dimer of the polypeptide chain present in form 1, while form 2, present in a very low amount, consists of a polypeptide chain quite similar in aminoacid composition to that found in form 1. The three molecular forms show very similar kinetic parameters. The comparison of these molecular forms with those isolated from horse muscle showed similar kinetic properties but different structural features.

Acid Anhydride Hydrolases↗