V O L. 5 3, N. 4 D E C E M B E R 2004

Suicidal Dephosphorylation of Thiamine Pyrophosphate Coupled with Pyruvate Dehydrogenase Complex
Slawomir Strumilo, Pawel Dobrzyn, Jan Czerniecki, Adam Tylicki
The Italian Journal of Biochemistry: 2004; 53(4): 131-134

Abstract. Earlier it was noted that purified pyruvate dehydrogenase complex (PDC) produced by "Sigma" usually contains almost saturating amounts of thiamine pyrophosphate (ThPP). In this communication we present the observation that the endogenous ThPP coupled to PDC is dephosphorylated while staying at -10 ÉC, because in the enzyme preparation thiamine monophosphate and un-phosphorylated thiamine appear (HPLC determination). Under the same conditions exogenous ThPP is not dephosphorylated despite contact with the PDC preparation. This may suggest that interactions of some active groups of the enzyme with molecules of endogenous ThPP leads to break-up of the phosphoesters bonds, and destruction of the coenzyme. Decrease of PDC activity during storage is not in proportion with the degree of ThPP dephosphorylation. However the observed instability of PDC activity may be a consequence of the spontaneous process of its coenzyme autodestruction.

Acute regulation of the facilitative glucose transporter GLUT1 in a hematopoietic cell line
Gabriele Hakim, Diana Fiorentini, Tullia Maraldi and Laura Landi
The Italian Journal of Biochemistry: 2004; 53(4): 135-140

Abstract. This brief review is focused on the short-term regulation of the facilitative glucose transporter GLUT1 in megakaryocytic cells M07e. The effects of cytokines such as TPO, GM-CSF and SCF and of a low dose of H2O2 on the transport activity and its kinetic parameters are compared. The possible mechanisms and the signalling pathways involved in the glucose uptake activation are discussed. A role for the cellular redox status in glucose uptake control, possibly related to the status of redox-sensitive enzymes such as tyrosine phosphatases, is suggested.

Adenosine: old passion, new perspectives
Lucacchini Antonio and M. Letizia Trincavelli
The Italian Journal of Biochemistry: 2004; 53(4): 141-147

Abstract. In this review is summarized my research in the adenosine field from the beginning of my carrier to day. My research began preparing the degree thesis with Prof. Carlo Alfonso Rossi, about the purification and characterization of adenosine deaminase. My scientific interest for adenosine has spread during the years and I have been interested in the study of ARs and their related transduction and in the study of molecular mechanisms involved in homologous and heterologous AR receptor regulation.

Guanidine-induced dissociation of mitochondrial F1-ATPase
Stavros Papageorgiou and Giancarlo Solaini
The Italian Journal of Biochemistry: 2004; 53(4): 148-156

Abstract. The effect of guanidine hydrochloride on ATPase activity, gel filtration, turbidity, and the fluorescence emission intensity of mitochondrial F1-ATPase was examined. Purified F1 from bovine heart mitochondria was slowly inactivated at low denaturant concentration, and inactivation was associated with ? and ? subunit dissociation. ? and ? subunits were bound together to form a stable and soluble heterodimer. In parallel, appearance of turbidity was observed. This was caused by the formation of ?3?3? non-covalent aggregates, as analyzed by SDS-PAGE. Short periods of exposition of the F1 complex to high concentrations of guanidine hydrochloride (0.8-3 M) again induced ?? dissociation as a heterodimer and the formation of an inactive ?3?3g subcomplex. This eventually dissociated progressively into single subunits caused by partial unfolding, as evidenced through changes of the protein intrinsic fluorescence emission. Our results suggest that the ? and ? subunits are loosely bound to ?3?3? , and play an important role in determining structural stability to isolated mitochondrial F1-ATPase.

Nutritional interventions to counteract oxidative stress in cardiac cells
Silvana Hrelia, Alessandra Bordoni, Cristina Angeloni, Emanuela Leoncini, and PierLuigi Biagi
The Italian Journal of Biochemistry: 2004; 53(4): 157-163

Abstract. Preventing oxidative damage in the heart is subject of considerable investigation and studies developing nutritional intervention methods to attenuate or prevent the resulting pathological state of free radical damage are now emerging. In this light, a dietary intervention directed to increase the daily intake of antioxidant molecules represents a fundamental step to achieve a beneficial result. In this minireview the attention is focused on the damage induced in cultured cardiac cells by the antitumoral doxorubicin, known for its cardiotoxicity, and by hypoxia/ reoxygenation that occur in a wide variety of important clinical conditions. The identification of antioxidant molecules having specific effectiveness in a particular cell type may be useful for the development of a prevention strategy specific for free radical induced-diseases related to that cell type. Although the connection between consumption of foods rich in polyphenolic compounds and the decreased risk of cardiovascular disease has been reported, the role of different antioxidant molecules contained in foods is still to be elucidated. The protective effect of the polyphenolic components of green tea in the prevention/counteraction of cell damage induced in the heart by doxorubicin or hypoxia/reoxygenation has been discussed.

Twenty years of hunting for proteins with Carlo Alfonso Rossi
Fiorenzo Stirpe
The Italian Journal of Biochemistry: 2004; 53(4): 164-168

Abstract. The research accomplished in more thanr twenty years of collaboration with Carlo Alfonso Rossi is reviewed. Several lectins and toxic and non-toxic ribosome-inactivating proteins were identified, purified and characterized. The general properties of the proteins are described.

Evaluation of the lipid composition of human healthy and neoplastic renal tissues
Vitaliano Tugnoli, Andrea Trinchero and Maria Raffaella Tosi
The Italian Journal of Biochemistry: 2004; 53(4): 169-182

Abstract. The assumption that kidney tumors are characterized by high lipid content has directed our research towards the evaluation and comparison of lipids in healthy and neoplastic human renal tissues. This research appears to have marked importance owing to the role of lipids in cancer cell biochemistry. Nuclear Magnetic Resonance spectroscopy and chromatographic methods allow the full description of the lipidic profile typical of intact medulla, intact cortex, clear-cell renal carcinomas, chromophobe-cell renal carcinomas, oncocytomas and two samples of medulla infiltrated by a nephrocarcinoma. Significant differences among healthy, benign and malignant tissues were shown, and the results were discussed in relation to the different roles of each lipidic component and compared with the literature data.