Karboksilesteraza djelomice hidrolizira estere gama-butirobetaina u serumu štakora

Although described some time ago, gamma-butyrobetaine esters and related compounds have not gained much attention from researchers, and their physiological function remains obscure. Formerly we detected GBB-esterase enzymatic activity in rat blood serum using phenylated gamma-butyrobetaine as an artificial substrate of the enzyme and HPLC. The aim of the present work was to develop an assay that would enable spectrophotometric or colorimetric determination of the reaction products of GBB-esterase activity and to reveal individual proteins performing GBB-esterase activity in rat blood serum. For this purpose gammabutyrobetaine 1-naphthyl ester was synthesised. Hydrolysis of this ester releases 1-naphthol, which increases the optical absorbance at 322 nm. We have shown that the enzymatic hydrolysis of GBB 1-naphthyl ester to 1-naphthol in rat blood serum is due to GBB-esterase activity. An attempt was done to purify the enzyme from rat blood serum. By combining DEAE Sepharose at pH 4.2 and affinity chromatography with procainamide we achieved a 68-fold enrichment of GBB-esterase activity in our preparations. Separation of fraction proteins in 2D protein electrophoresis with following mass-spectrometry indicated that GBB esterase activity in rat blood serum is performed in part by carboxylesterase.Premda su poznati već neko vrijeme, esteri gama-butirobetaina (GBB) i srodni spojevi nisu dobili mnogo pozornosti u znanstvenoistraživačkoj zajednici, a njihova fiziološka funkcija i dalje je nerazjašnjena. U ranijem smo istraživanju HPLC-metodom otkrili enzimsku aktivnost GBB-esteraze u serumu štakora rabeći umjetni supstrat ovoga enzima, tj. fenilirani gama-butirobetain. Cilj ovoga istraživanja bio je razviti pretragu koja će omogućiti spektrofotometrijsko ili kolorimetrijsko određivanje reakcijskih produkata nastalih aktivnošću GBB-esteraze te utvrditi koji pojedinačni proteini u serumu štakora posjeduju aktivnost GBB-esteraze. U tu je svrhu sintetiziran gama-butirobetain 1-naftil ester. Njegovom hidrolizom otpušta se 1-naftol koji povećava optičku apsorbanciju na 322 nm. Pokazali smo da u hidrolizi GBB 1-naftil estera u 1-naftol u serumu štakora sudjeluje GBB-esteraza. Pokušali smo pročistiti enzim iz štakorskoga seruma. Kombinacijom DEAE sefaroze pri pH 4,2 i afinitetne kromatografije s prokainamidom dobili smo 68-erostruko povećanje aktivnosti ovoga enzima. Razdvajanjem bjelančevina iz frakcije s pomoću 2D elektroforeze te naknadnom spektrometrijom masa utvrđeno je da u serumu štakora esteraznu aktivnost prema gama-butirobetainu kao supstratu djelomice provodi karboksilesteraza

Molecular alterations in signal pathways of melanoma and new personalized treatment strategies: Targeting of Notch

Despite modern achievements in therapy of malignant melanomas new treatment strategies are welcomed in clinics for survival of patients. Now it is supposed that personalized molecular therapies for each patient are needed concerning a specificity of molecular alterations in patient's tumors. In human melanoma, Notch signaling interacts with other pathways, including MAPK, PI3K-AKT, NF-kB, and p53. This article discusses mutated genes and leading aberrant signal pathways in human melanoma which are of interest concerning to their perspective for personalized treatment strategies in melanoma. We speculate that E3 ubiquitin ligases MDM2 and MDM4 can be attractive therapeutic target for p53 and Notch signaling pathways in malignant melanoma by using small molecule inhibitors. It is possible that restoration of p53-MDM2-NUMB complexes in melanoma can restore wild type p53 function and positively modulate Notch pathway. In this review we summarize recent data about novel US Food and Drug Administration approved target drugs for metastatic melanoma treatment, and suppose model for treatment strategy by targeting Notch

Širdies audinių ekstraktų tyrimas spektroskopijos metodais

The conduction system of the heart (HCS) is a type of muscular tissue which generates and transmits bioelectrical impulses. During surgical operations it is possible to harm HCS, since the common origin makes it hardly discernible for an unaided eye in the surroundings of ordinary myocardium (MC) or endocardium. The aim of this study was to reveal the protein composition differences between His bundle (HB) and MC tissues and to determine the distribution of fluorophores in these tissues. This in turn would help to visualize HCS by means of optical-fluorescence biopsy. It has been shown that fluorescence of the soluble fractions of heart tissues is mainly determined by tryptophan (W) and tyrosine (Y) residue emission, while fluorophores, responsible for the fluorescence in the visible region, were found to be hardly extractable from tissues and precipitated out as the insoluble fraction. According to SDS-PAGE, some protein groups specific to MC and HB were revealed. Some SDS-PAGE gel sections containing certain proteins of heart tissue fractions were investigated by spectroscopic methods. The results indicated that proteins of the same weight extracted from different heart tissues exhibit different fluorescence spectra

Purification and characterization of a new β-lactamase OXA-205 from Pseudomonas aeruginosa

Background We have identified a novel class 1 integron (1503 bp), named In671 in a clinical Pseudomonas aeruginosa isolate. Integron sequence analysis revealed two gene cassettes, one coding for a new OXA-type β-lactamase designated as OXA-205 and the other coding for the aadB gene that is responsible for aminoglycoside resistance. The 266 amino acid sequence of OXA-205 revealed that this β-lactamase belongs to the Ambler class D showing highest sequence homology to the OXA-2 sub-lineage. Our objective was to purify and characterize β-lactamase OXA-205. Methods Escherichia coli cells were transformed with a plasmid containing cloned bla OXA-205 gene from P. aeruginosa. Purification of overproduced OXA-205 consisted of a single ion-exchange chromatography step. SDS-PAGE and isoelectric focusing were performed to determine the molecular mass and pI, respectively. Size-exclusion chromatography was undertaken to determine the OXA-205 oligomerization state. Substrate hydrolysis reactions were employed to assess enzyme kinetic parameters. Results Purification of OXA-205 yielded the enzyme with >95 % purity (as verified by SDS-PAGE). Approximate yield of the protein was estimated to be 20 mg per liter of culture. OXA-205 had a pI at 8.1, molecular mass of 26 kDa and a monomeric native structure. Kinetic analysis revealed that OXA-205 hydrolyzed narrow spectrum substrates, including ampicillin, carbenicillin, oxacillin, penicillin G, cefazolin and cefuroxime. Additionally, we observed a substrate inhibition profile towards carbenicillin and oxacillin, but not with ampicillin or penicillin G. Our results also show that OXA-205 conferred unusually high (among class D β-lactamases) resistance towards inhibition by NaCl. Conclusions OXA-205 can be considered a narrow spectrum monomeric β-lactamase that demonstrates unusually high resistance profile towards inhibition by NaCl