In this study we assessed the applicability of the recently reported ancestral l-amino acid oxidase (AncLAAO), for the development of an enzyme-coupled phenylalanine ammonia-lyase (PAL) activity assay. Firstly, the expression and isolation of the AncLAAO-N1 was optimized, followed by activity tests of the obtained octameric N-terminal His-tagged enzyme towards various phenylalanine analogues to assess the compatibility of its substrate scope with that of the well-characterized PALs. AncLAAO-N1 showed high catalytic efficiency towards phenylalanines mono-, di-, or multiple-substituted in the meta- or para-positions, with ortho- substituted substrates being poorly transformed, these results highlighting the significant overlap between its substrate scope and those of PALs.
View Article and Find Full Text PDFPhenylalanine ammonia-lyases (PALs) catalyse the non-oxidative deamination of l-phenylalanine to -cinnamic acid, while in the presence of high ammonia concentration, the synthetically attractive reverse reaction occurs. Although they have been intensively studied, the wider application of PALs for the large scale synthesis of non-natural amino acids is still rather limited, mainly due to the decreased operational stability of PALs under the high ammonia concentration conditions of ammonia addition. Herein, we describe the development of a highly stable and active immobilized PAL-biocatalyst obtained through site-specific covalent immobilization onto single-walled carbon nanotubes (SWCNTs), employing maleimide/thiol coupling of engineered enzymes containing surficial Cys residues.
View Article and Find Full Text PDFBackground: Cardiac tumors are very uncommon compared to other cardiac diseases. Their clinical symptoms can vary from absent to non-specific. The most common symptoms are arrhythmias, blood flow obstruction due to valvular dysfunction, shortness of breath, systemic embolization, and accumulation of pericardial fluid.
View Article and Find Full Text PDFPulmonary arterial intimal sarcoma is a rare tumour with high mortality. Due to its localisation, the symptoms can mimic pulmonary thromboembolism and pneumonia, therefore assessing the diagnosis and choosing the adequate therapy is never easy. Its therapy mainly consists of surgery combined with radiochemotherapy.
View Article and Find Full Text PDFAdriamycin is a potent anthracycline-type antitumor agent, but it also exerts potentially serious side effects due to its cardiotoxic and neurotoxic propensity. Multiple impairments in sensory nerve functions have been recently reported in various rat models. The present experiments were initiated in an attempt to reveal adriamycin-induced changes in sensory effector functions of chemosensitive meningeal afferents.
View Article and Find Full Text PDFThe present study was aimed to develop a medium-throughput screening technique for investigation of cyclodextrin (CD)-active pharmaceutical ingredient (API) complexes. Dual-phase potentiometric lipophilicity measurement, as gold standard technique, was combined with the partition coefficient method (plotting the reciprocal of partition coefficients of APIs as a function of CD concentration). A general equation was derived for determination of stability constants of 1:1 CD-API complexes (K) based on solely the changes of partition coefficients (logP-logP), without measurement of the actual API concentrations.
View Article and Find Full Text PDFNaunyn Schmiedebergs Arch Pharmacol
September 2016
Besides their deleterious action on cardiac muscle, anthracycline-type cytostatic agents exert significant neurotoxic effects on primary sensory neurons. Since cardiac sensory nerves confer protective effects on heart muscle and share common traits with cutaneous chemosensitive nerves, this study examined the effects of cardiotoxic doses of adriamycin on the function and morphology of epidermal nerves. Sensory neurogenic vasodilatation, plasma extravasation, and the neural CGRP release evoked by TRPV1 and TRPA1 agonists in vitro were examined by using laser Doppler flowmetry, the Evans blue technique, and ELISA, respectively.
View Article and Find Full Text PDFNaunyn Schmiedebergs Arch Pharmacol
December 2004
Capsaicin-sensitive sensory nerves that contain calcitonin gene-related peptide (CGRP) contribute significantly to cardioprotective mechanisms. In this study, the possible role of capsaicin-sensitive afferent nerves in the development of congestive heart failure was examined in an established model of adriamycin-induced experimental cardiomyopathy in rats. Systemic treatment with capsaicin was utilized to deplete sensory neuropeptides from cardiac afferent nerves.
View Article and Find Full Text PDF