P.A. Biondi

A biotin-avidin sandwich enzyme-linked immunosorbent assay of growth hormone in bovine plasma

Purified pituitary bovine growth hormone (bGH) has been used to develop a homologous sandwich enzyme-linked immunosorbent assay in which affinity-purified antibodies are immobilized on microtiter plates. Bovine GH bound to specific antibody is then revealed with a second anti-bGH antibody labeled with biotin and peroxidase-conjugated avidin. The method requires only 48 h, including the coating step, and has a sensitivity as low as 0.25 ng/ml of bGH. Statistical analyses (test of parallelism, cross-reactivity among bGH and GH of various species and bovine prolactin, recovery test, within- and between-assay variation, comparison with radioimmunoassay) confirm the high specificity and reproducibility of the method.

Different Fibres for the Analysis of Volatile Compounds in Processed Meat Products by Solid Phase Micro-Extraction (SPME)

L.M. Chiesa1,∗, S. Soncin1, P.A. Biondi2, P. Cattaneo1 and C. Cantoni1 1Laboratory of Food Inspection, Department of Veterinary Sciences and Technologies for Food Safety, Faculty of Veterinary Medicine, University of Milan, Milan, Italy; 2Laboratory of Food Biochemistry, Department of Veterinary Sciences and Technologies for Food Safety, Faculty of Veterinary Medicine, University of Milan, Milan, Italy ∗Correspondence: E-mail: luca.chiesa@unimi.it

New Derivatives Suitable for Use in Determination of (3-Methoxy-4-Hydroxyphenyl)Ethyleneglycol (MHPG) by Mass Fragmentography (MF)

Abstract (3-methoxy-4-hydroxyphenyl)ethyleneglycol (MHPG) is acylated at the phenolic group with acetic anhydride, and the product is condensed with methaneboronic or butaneboronic acids. The derivatives so obtained are suitable for selective ion-monitoring during combined gas chromatography/mass spectrometry since, after the loss of the acetyl group, very abundant ions of MHPG-bo ronates are obtained.

Preparative electrophoresis for large scale preparation of highly purified bovine growth hormone

A method allowing large scale preparation of bovine growth hormone from pituitary glands in relatively few steps is described. In comparison to conventional purification techniques previously reported, the use of preparative polyacrylamide gel electrophoresis reduces the number of steps and the amount of time needed for the isolation of the hormone. In addition, the yield is several times greater, the hormone is purer and it has greater bioactivity (1.83 IU/mg).

High-performance liquid chromatographic assay of bacterial collagenase

SummaryThe activity of bacterial collagenase Clostridiopeptidase A was estimated using a labelled synthetic peptide, 4-phenylazobenzyloxycarbonyl-L-Pro-L-Leu-Gly-L-Pro-D-Arg, as substrate. The N-protected dipeptide obtained after enzymatic hydrolysis of Leu-Gly peptide bond was quantified by reversed-phase, high-performance liquid chromatography using 4-phenylazobenzyloxycarbonyl-L-Pro-L-Phe as internal standard. The time dependence of the appearance of the hydrolysis product and the dependence of rates of hydrolysis on collagenase concentration were linear. Kinetic parameters for collagenase were determined to test the suitability of the described procedure.

Studies on Analogues of Succinic Semialdehyde as Substrates for Succinate Semialdehyde Dehydrogenase from Rat Brain

The methyl ester of succinic semialdehyde (SSA) was examined as a substrate for succinate semialdehyde dehydrogenase (SSADH) from rat brain. It was found that the ester can be oxidized by the enzyme. Values of Km for SSA‐Me were higher than for those for SSA, and for this substrate the enzyme showed a substrate‐dependent inhibition. This finding suggests that the carboxylate group of SSA is not essential in the process of inhibition of SSADH by the substrate. Cyclopropyl analogues of SSA, cis‐ and trans‐1‐formyl‐cyclopropan‐2‐carboxylic acids, were also individually tested as substrates of SSADH. Only the trans isomer was found to be oxidized to the corresponding dicarboxylic acid; it inhibited the enzyme in the same range of concentrations as SSA. The above data suggest that, as for γ‐aminobutyric acid, SSA is present in an unfolded, transoid conformation at the active site of SSADH.

Regioselectivity in the oxidative deamination of 2-methyl-1,4-diaminobutane catalyzed by diamine oxidases

Diamine oxidase from pea seedlings (PDAO) catalyzes the oxidation of 2-methyl-1,4-diaminobutane in a regioselective fashion, whereas diamine oxidase from pig kidney (KDAO) shows no regioselectivity for the same reaction.

New Derivatives of (3,4-Dihydroxyphenyl)ethyleneglycol (DHPG) Suitable for Mass Fragmentography (MF)

Abstract (3,4-dihydroxyphenyl)ethyleneglycol (DHPG) is condensed with methaneboronic or n-butaneboronic acids with or without previous acetylation of the phenolic groups. The derivatives so obtained are suitable for selective ion monitoring during gas chromatographic/ mass spectrometric analysis of DHPG alone or together with (3-methoxy-4-hydroxyphenyl)ethyleneglycol (MHPG).