diamine oxidase

A highly selective, sensitive, specific and rapid electrochemical putrescine biosensor was constructed by covalently immobilizing diamine oxidase purified from Pisum sativum  leaves on polypyrrole 3-carboxylic acid (PPy-3C) with zinc oxide nanoparticles ( ZnONps) using N-ethyl-N-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) modified platinum electrode.Transmission electron microscopy (TEM), X-ray diffraction (XRD), UV spectroscopy and Dynamic light scattering (DLS) were used for characterization of ZnONps. The modified enzyme electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS).The experimental variables that can affect the putrescine amperometric response, such as the applied potential, pH and temperature have been optimized to perform a selective determination of putrescine.The optimized putrescine biosensor showed linear response range of 0.1–750µM and rapid response within 4s at a potential of 0.4V vs Ag/AgCl. The sensitivity was approximately 40µA/mM/cm2 with a detection limit of 0.1µM. Proposed putrescine biosensor was successfully applied to cancer patients urine sample, which correlated well with a standard enzymic colorimetric method (r = 0.98).

Abstract
(maximum 200 words) Diamine oxidase (DAO) is a key enzyme of the metabolism of polyamines. Its activity was assayed in homogenate of male immature rat liver and kidney.  The androgens are important regulators of polyamines’ metabolism. It was known that testosterone (T) activates DAO in murine kidney, an effect that might depend on the intracellular level of polyamines. The aim of this research was to study the participation of androgen receptor and ornithine decarboxylase (ODC) in DAO testosterone regulation. The rats were treated i.p. 4 hours before measurements with T, T + Hydroxyflutamide (HF), an androgen receptor antagonist or T + difluoromethylornithine (DFMO), an inhibitor of ODC. It was observed that i) T significantly increased DAO activity of rat liver and kidney; ii) the presence of HF abolished the effect of T; iii) the presence of DFMO reduced the effect of T on DAO activity. It is concluded that T activates DAO mainly by a mechanism, which includes androgen receptor binding and ODC stimulation.

SUMMARY Diamine oxidase (DAO) activity was determined in internodes and leaves of faba bean (Vicia faba L.) culti- vars susceptible and resistant to Ascochyta blight. DAO activity was measured in stems and leaves of whole plants and on detached leaves, untreated or inoculated with a highly virulent Ascochyta fabae isolate. DAO ac- tivity was higher in leaves than in stems,