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61.
Francesca Paoletti Sonia Covaceuszach Peter V. Konarev Stefania Gonfloni Francesca Malerba Elisabeth Schwarz Dmitri I. Svergun Antonino Cattaneo Doriano Lamba 《Proteins》2009,75(4):990-1009
The unprocessed precursor of the Nerve Growth Factor (NGF), proNGF, has additional functions, besides its initially described role as a chaperone for NGF folding. The precursor protein endows apoptotic and/or neurotrophic properties, in contrast to the mature part. The structural and molecular basis for such distinct activities are presently unknown. Aiming to gain insights into the specific molecular interactions that govern rm‐proNGF biological activities versus those of its mature counterpart, a structural study by synchrotron small angle X‐ray scattering (SAXS) in solution was carried out. The different binding properties of the two proteins were investigated by surface plasmon resonance (SPR) using, as structural probes, a panel of anti‐NGF antibodies and the soluble forms of TrkA and p75NTR receptors. SAXS measurements revealed the rm‐proNGF to be dimeric and anisometric, with the propeptide domain being intrinsically unstructured. Ab initio reconstructions assuming twofold symmetry generated two types of structural models, a globular “crab‐like” and an elongated shape that resulted in equally good fits of the scattering data. A novel method accounting for possible coexistence of different conformations contributing to the experimental scattering pattern, with no symmetry constraints, suggests the “crab‐like” to be a more likely proNGF conformation. To exploit the potential of chemical stabilizers affecting the existing conformational protein populations, SAXS data were also collected in the presence of ammonium sulphate. An increase of the proNGF compactness was observed. SPR data pinpoints that the propeptide of proNGF may act as an intrinsically unstructured protein domain, characterized by a molecular promiscuity in the interaction/binding to multiple partners (TrkA and p75NTR receptors and a panel of neutralizing anti‐NGF antibodies) depending on the physiological conditions of the cell. These data provide a first insight into the structural basis for the selectivity of mouse short proNGF, versus NGF, towards its binding partners. Proteins 2009. © 2008 Wiley‐Liss, Inc. 相似文献
62.
The open reading frame PA3859 of Pseudomonas aeruginosa encodes an intracellular carboxylesterase belonging to a group of microbial enzymes (EC 3.1.1.1) that catalyze the hydrolysis of aliphatic and aromatic esters with a broad substrate specificity. With few exceptions, for this class of enzymes, belonging to the α/β-hydrolase fold superfamily, very little information is available regarding their biochemical activity and in vivo function. The X-ray crystal structure of recombinant PA3859 has been determined for two crystal forms (space groups P21 and P21212). The kinetic properties of the enzyme were studied using p-nitrophenyl esters as substrates and data fitted to a surface dilution mixed micelle kinetic model. Enzymatic assays and computational docking simulations, pinpointed the enzyme’s preference for esters of palmitic and/or stearic acids and provided insights into the enzyme–substrate favorable binding modes. 相似文献
63.
Silvestro Duprè Giuseppe Spoto Rosa Marina Matarese Mariella Orlando Doriano Cavallini 《Archives of biochemistry and biophysics》1980,202(2):361-365
After injection of various 35S- and 14C-containing compounds, the incorporation of the label into the lipoic acid present in the liver of growing rats has been determined. The best precursor for sulfur atoms, after 24 h, is cysteine; methionine and cystamine are scarcely incorporated and thiosulfate not at all. Good precursors of the carbon moiety are acetate and octanoate, whereas the incorporation of butyrate and cysteine is very low. It is concluded that lipoic acid is biosynthesized in the rat liver, and that sulfur atoms probably originate from cysteine. 相似文献