1,721,039 research outputs found
FUNCTIONAL RESIDUES AT THE ACTIVE SITE OF HORSE LIVER PHOSPHOPANTOTHENOYLCYSTEINE DECARBOXYLASE.
No full textHorse liver phosphopantothenoylcysteine decarboxylase (EC 4.1.1.36) is rapidly inactivated by N-acetoacetylation with diketene following a pseudo-first-order kinetics: the presence of substrate quantitatively protects against this inactivation. Histidine photo-oxidation with methylene blue or rose bengal brings about the total loss of activity. These results indicate the presence of functional lysyl and histidyl groups at the active site of the enzyme. The substrate sulphydryl group is essential for enzyme activity. Enzymatic decarboxylation is proposed to result from a combined action of the keto group of the enzyme-bound pyruvate protonated by an essential histidine and a protonated amino group of a lysine
Chaperones, chaperonins and heat-shock proteins
No full textThe protein folding of a nascent polypeptide is
the decoding of the linear information contained
in the primary sequence into the native and functionally
active three-dimensional conformation.
Chaperone proteins and folding catalysts may
contribute to successful folding into the native
and active protein conformation in the crowded
cellular environment, thus avoiding aggregation
of non-native protein forms. Molecular chaperones
in vivo play a pivotal role in the maintenance of
the proteome quality control and in the correct
balance between protein folding and degradation.
The unbalance of the equilibrium between protein
synthesis, protein folding and protein degradation
may contribute to protein misfolding and
aggregation which may lead to the onset of several
degenerative diseases associated with protein
aggregation, such as Alzheimer’s and Huntington’s
disease
Fondamenti di biochimica umana
No full textIn quest’opera gli aspetti più importanti della biochimica umana sono stati raggruppati in tre temi unificanti: biomolecole funzionali e strutturali (vitamine,
modulatori dello stress ossidativo, ormoni e lipidi bioattivi, neurotrasmettitori e componenti del citoscheletro); biochimica d’organo (cuore, fegato, apparato
digerente, reni, sangue, apparato riproduttivo, apparato
muscolare, osso, tessuto adiposo, cute e sistema nervoso); biochimica speciale (biochimica del tumore, fecondazione e sviluppo embrionale, metalli, stato redox
e infiammazione, biochimica dei sensi, biochimica della
nutrizione e biochimica clinica
Proto-oncogene Pim-1: structural stability of the variants observed in tumor tissues
No full textPim-1 kinase belongs to the family of serine/threonine protein kinases (EC 2.7.11.1) encoded by the pim proto-oncogenes (Saris et al., 1991; Hoover et al., 1991; van der Lugt et al., 1995). Pim-1 kinase, originally identified as a common Proviral insertion site in moloney murine leukemia virus-induced T-cell lymphomas in mice (Cuypers et al., 1984), is involved in several signalling pathways and in the regulation of cell cycle progression and apoptosis. The three Pim family members Pim-1, Pim-2 and Pim-3 identified in humans have been reported as signalling protein kinases playing an important role in tumor biology (Anizon et al., 2010). Pim-1, nearly undetectable in normal tissues, is overexpressed in many haematological malignancies and in the cells of several solid tumor. In several cancer tissues Pim-1 variants have been identified and several databases for patterns of somatic mutation in human cancer genomes report mutations in this oncogene (Yuan et al., 2006; Greenman et al., 2007; Forbes et al., 2008; Akagi et al., 2009). Many of these variants are nonsynonymous single nucleotide polymorphisms (nsSNPs), single nucleotide variations occurring in the coding region and leading to amino acid substitutions (Dixit A et al., 2009). In this study we investigated the effect of amino acid substitution on the structural stability and on the activity of the Pim-1 kinase. We expressed and purified as soluble recombinant proteins some of the mutants identified in cancer and in the nsSNPs database. The mutants show a decreased thermal and thermodynamic stability and decreased activation energy relative to kinase activity, when compared to the wild- type
Acid-induced disassembly of glutamate dehydrogenase from the hyperthermophilic archaeon Pyrococcus furiosus occurs below pH 2.0
No full textI.F.= 3.24
Phosphopantothenoylcysteine decarboxylase from horse liver [4'-phospho-N-(D-pantothenoyl)-L-cysteine carboxy-lyase, EC 4.1.1.36].
No full textBeta-Sheet-breaker peptides containing alfa, beta-dehydrophenylalanine: synthesis and in vitro activity studies
No full textThe synthesis and fibrillogenesis-inhibiting activity of the new peptide derivatives 1–6, containing α,β-unsaturated phenylalanines, are reported. These compounds are related to the pentapeptide Ac-LPFFD-NH2 (iAβ5p), which was designed by Soto and co-workers and is commonly accepted as a lead compound for fibrillogenesis inhibition . Their activities are determined by Thioflavin T binding assay, far-UV circular dichroism (CD) spectroscopy , and SEM; in addition, their structures in solution are studied through far-UV CD and FTIR spectroscopy. The presence of two α,β-unsaturated phenylalanines increases the fibrillogenesis inhibiting activity significantly in comparison with the lead compound. The interactions between the Aβ1–40 and the inhibitors using electrospray ionization mass spectrometry are also studied. The analyses prove the presence of noncovalent complexes of Aβ1–40 with iAβ5p and its derivatives 1–3 with stoichiometries of 1:1 and 2:1, and the results are independent of time and Aβ1–40/inhibitor rati
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