Structural and Functional Characterization of a New Double Variant Haemoglobin (HbG-Philadelphia/Duarte α268Asn→Lysβ262Ala→Pro)

We report the first case of cosegregation of two haemoglobins (Hbs): HbG-Philadelphia [α68(E17)Asn → Lys] and HbDuarte [β62(E6)Ala → Pro]. The proband is a young patient heterozygous also for β°-thalassaemia. We detected exclusively two haemoglobin variants: HbDuarte and HbG-Philadelphia/Duarte. Functional study of the new double variant HbG-Philadelphia/Duarte exhibited an increase in oxygen affinity, with a slight decrease of cooperativity and Bohr effect. This functional behaviour is attributed to β62Ala → Pro instead of α68Asn → Lys substitution. Indeed, HbG-Philadelphia isolated in our laboratory from blood cells donor carrier for this variant is not affected by any functional modification, whereas purified Hb Duarte showed functional properties very similar to the double variant. NMR and MD simulation studies confirmed that the presence of Pro instead of Ala at the β62 position produces displacement of the E helix and modifications of the tertiary structure. The substitution α68(E17)Asn → Lys does not cause significant structural and dynamical modifications of the protein. A possible structure-based rational of substitution effects is suggested

Tyrosinase inhibitor activity of coumarin-resveratrol hybrids

In the present work we report on the contribution of the coumarin moiety to tyrosinase inhibition. Coumarin-resveratrol hybrids 1-8 have been resynthesized to investigate the structure-activity relationships and the IC50 values of these compounds were measured. The results showed that these compounds exhibited tyrosinase inhibitory activity. Compound 3-(3’,4’,5’-trihydroxyphenyl)-6,8-dihydroxycoumarin (8)is the most potentcompound (0.27 mM), more so than umbelliferone (0.42 mM), used as reference compound. The kinetic studies revealed that compound 8 caused non-competitive tyrosinase inhibitionWe thank Progetto di Ricerca Scientifica 2007-Università di Cagliari and Fondazione del Banco di Sardegna, Xunta de Galicia (PGIDIT05PXIB20304PR) and Ministerio de Sanidad y Consumo (FIS PI061537 and PI061457) for financial supportS

Purine metabolites in fibromyalgia syndrome

OBJECTIVE: To evaluate serum purine metabolite concentrations in patients affected by fibromyalgia syndrome (FMS) and the relationships between their levels and FM clinical parameters. DESIGN AND METHODS: Serum purine levels were quantified using LC/UV-vis in 22 fibromyalgic females (according to the American College of Rheumatology classification criteria) and 22 healthy females. RESULTS: Significantly higher serum inosine, hypoxanthine and xanthine levels (p<0.001) and significantly lower serum adenosine (p<0.05) were detected in the FMS patients vs healthy controls. Our data show a negative correlation between adenosine and Fibromyalgia Impact Questionnaire (FIQ). CONCLUSIONS: Study results suggest that purines, in particular adenosine and inosine, may be involved in pain transmission in fibromyalgia

Increase in urinary purines and pyrimidines in patients with methylmalonic aciduria combined with homocystinuria

Background: Methylmalonic aciduria combined with homocystinuria (MMA–HC) is the biochemical trait of a metabolic disorder resulting from impaired conversion of dietary cobalamin (cbl, or vitamin B12) to its two metabolically active forms. Effects on urinary purine and pyrimidine levels have not been described for this condition. Methods: Urine samples were collected from three patients with methylmalonic aciduria combined with homocystinuria and from 70 healthy subjects. Urinary purine and pyrimidine levels were quantitated by the use of LC/UV–Vis and LC/ESI/MS. Results: Higher urine levels of pyrimidines were detected with both methods in patients compared to controls. Conclusion: Methylmalonic aciduria with homocystinuria is due to deficiency of the enzyme, cobalamin reductase. The enzyme defect leads to altered hepatic metabolism, which appears to modify circulating pyrimidine levels

The hemoglobin polymorphism of the Sardinian wild dwarf horse and the oxygen binding properties of the four different horse hemoglobins

A study was made of the Hb phenotype of the Sardinian dwarfhorse (Equus caballus jara), one of the last surviving wild horse species in Europe. Hb haplotypes and their frequencies were found to be similar to those described in the Arabian horse (BI = 0.551, BII = 0.389, A = 0.036, V = 0.015), which suggests possible introduction onto the island from North Africa. The oxygen binding properties of the whole hemolysates and of the four different horse Hbs, separated by ion-exchange chromatography, were considered with regard to the effect of chloride, 2,3-bisphosphoglycerate and lactate. Results indicate that no differences exist in the four components that characterize horse Hb. The molecular basis of the intrinsically low oxygen affinity and of the weak interaction of horse Hb with 2,3-bisphosphoglycerate is discussed in the light of the primary structure of the molecule

New halogenated phenylcoumarins as tyrosinase inhibitors

With the aim to find out structural features for the tyrosinase inhibitory activity, in the present communication we report the synthesis and pharmacological evaluation of a new series of phenylcoumarin derivatives with different number of hydroxyl or ether groups and bromo substituent in the scaffold. The synthesized compounds 5-12 were evaluated as mushroom tyrosinase inhibitors showing, two of them, lower IC 50 than the umbelliferone. Compound 12 (IC 50 = 215 μM) is the best tyrosinase inhibitor of this series

A Comparative study on the functional properties of the wild European mouflon and domestic sheep hemoglobins

The functional properties of Hb B of the wild European mouflon (Ovis gmelini musimon), Hb B of domestic sheep (Ovis aries), and Hb C isolated from anemic mouflon were investigated. Mouflon and sheep Hbs appear to be very similar in their response to organic anions and protons, whereas sheep Hb B displays an oxygen affinity lower than that of mouflon Hb B and sheep Hb A. Mouflon Hb B and Hb C, like sheep Hb A and Hb C, have similar efficiencies in transporting oxygen to the tissues. As in other ruminant Hbs, the effect of temperature on the oxygen affinity is slight. Data suggest that mouflon Hb B is not only structurally, but even functionally, more similar to sheep Hb A than to sheep Hb B