Biomedical subjects

D Pulcini

Publications and source records attributed to D Pulcini.

4 recordsLinked to original sources

PubMed1989

The molecular localization of non-tryptophan chromophores in calf lens crystallins.

A single-step separation of calf lens gamma-crystallin into six protein components is described. UV absorption spectra, characterized by the presence of high absorbance in the 240-250 nm and 310-360 nm spectral regions as well as by fluorescence emission above 400 nm, are shown by six components. alpha-, beta and beta S crystallins have been compared with the gamma-fraction for the presence of non-tryptophan fluorescence. The chromophores responsible for this non-tryptophan fluorescence were found to be associated with gamma-crystallin components only. The spectral features of one selected gamma-crystallin component (characterized by an isoelectric point of 7.68) have been examined. Results seem to suggest the presence of oxidative products of tryptophan. Implications of these findings for the expression of human and bovine genes are also considered.

Animals↗

PubMed1988

Presence of nontryptophan fluorophores specifically bound to gamma 2-crystallin.

alpha-, beta-, and gamma-crystallins have been purified from nonpathological lenses of calves. The pure proteins have been examined for nontryptophan fluorescence and fluorescent compounds have been found specifically bound to gamma 2-crystallin. The protein has been unfolded by 6 M guanidine hydrochloride (Gdn-HCl) and a separation of the fluorescent compounds has been obtained by gel chromatography in the presence of 6 M Gdn-HCl. The spectroscopic features (absorbance, fluorescence) of the protein returned to normal following removal of the chromophores. The low-molecular-weight separated fluorescent compounds have been fractionated and extracted from the Gdn-HCl solution by ethyl acetate. TLC chromatography has shown the presence of kynurenine, 3-OH-kynurenine, and free tryptophan. These data suggest that direct involvement of the intrinsic protein tryptophans in the photochemical processes leading to formation of fluorescent compounds has to be excluded. Free tryptophan and intrinsic metabolic factors are probably more relevant in determining the cataractous insult.

Animals↗

PubMed1985

Polycyclic aromatic hydrocarbon binding macromolecules. Identification, characterization and temperature activation of a 4.5 S binding nucleoprotein.

A macromolecule binding 3H-methylcholanthrene (3H-MCA) and 3H-benzo(a)pyrene (3H-BaP) and sedimenting in the 4-5 S region of sucrose gradient (4.5 S) was identified in rat liver cytosol. The binding was displaced by 100-fold molar excess unlabeled ligands whereas 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) was ineffective. The dissociation constant for both polycyclic aromatic hydrocarbons (PAHs) was of the order of 10(-8) M or lower. Both 3H-MCA and 3H-BaP bound to 4.5 S in a non covalent manner, since 92% of the bound radioactivity was extractable with ethyl ether. Furthermore the binding was strongly reduced by urea 8 M and by guanidine. HCl 4 M (99 and 70% respectively). Thin layer chromatography of the ethyl ether-solubilized radioactivity showed a peak comigrating with PAHs used as standards. When chromatographed on Sephadex G-200, 4.5 S was eluted as a sharp peak with an apparent molecular weight of 50-60,000 daltons. Enzyme treatment of liver cytosol showed that the 4.5 S binding sites were destroyed by micrococcal nuclease (92% of inhibition). Papain and phosphodiesterase I and II reduced the binding to 50%, whereas DNase I, DNase II, RNase, phospholipase A2 and C and trypsin were ineffective. These data suggest that the PAHs binding macromolecule of rat liver cytosol is a protein associated with a polynucleotide. The binding of both PAHs was enhanced by increasing the incubation temperature, the maximum being reached after 20-30 min at 37 degrees C. After 2.5 min at 65 degrees C, binding sites were completely destroyed. The same temperature-induced "activation" was obtained also by prewarming the cytosol at 37 degrees C in the absence of ligands.

Animals↗

PubMedDate not supplied

Alteration of serum tryptophan metabolism in patients suffering from senile cataract.

In vitro experimental evidence suggests tryptophan (TRP) is involved in protein modifications which could cause cataract formation in vivo. Previous studies of tryptophan plasma and serum metabolism are conflicting. In this study free and bound TRP plasma levels were measured in patients with senile cataract and in controls after an oral load of L-TRP (20 mg/kg b.w.). Free TRP levels were higher in patients than in controls one hour after L-TRP administration.

Administration, Oral↗