Folding mechanism of single domain antibody fragments (VHHs) and influence of the internal disulphide bridge on their stability and folding pathway.
Poster (2009, February)Detailed reference viewed: 21 (3 ULg)
Folding of class A beta-lactamases is rate-limited by peptide bond isomerization and occurs via parallel pathways.
Vandenameele, Julie ; Lejeune, Annabelle ; Di Paolo, Alexandre et al
in Biochemistry (2010), 49(19), 4264-75
Class A beta-lactamases (M(r) approximately 29000) provide good models for studying the folding mechanism of large monomeric proteins. In particular, the highly conserved cis peptide bond between residues ... [more ▼]
Class A beta-lactamases (M(r) approximately 29000) provide good models for studying the folding mechanism of large monomeric proteins. In particular, the highly conserved cis peptide bond between residues 166 and 167 at the active site of these enzymes controls important steps in their refolding reaction. In this work, we analyzed how conformational folding, reactivation, and cis/trans peptide bond isomerizations are interrelated in the folding kinetics of beta-lactamases that differ in the nature of the cis peptide bond, which involves a Pro167 in the BS3 and TEM-1 enzyme, a Leu167 in the NMCA enzyme, and which is missing in the PER-1 enzyme. The analysis of folding by spectroscopic probes and by the regain of enzymatic activity in combination with double-mixing procedures indicates that conformational folding can proceed when the 166-167 bond is still in the incorrect trans form. The very slow trans --> cis isomerization of the Glu166-Xaa167 peptide bond, however, controls the final step of folding and is required for the regain of the enzymatic activity. This very slow phase is absent in the refolding of PER-1, in which the Glu166-Ala167 peptide bond is trans. The double-mixing experiments revealed that a second slow kinetic phase is caused by the cis/trans isomerization of prolines that are trans in the folded proteins. The folding of beta-lactamases is best described by a model that involves parallel pathways. It highlights the role of peptide bond cis/trans isomerization as a kinetic determinant of folding. [less ▲]Detailed reference viewed: 55 (14 ULg)
The Folding Process of Hen Lysozyme: A Perspective from the 'New View'
Matagne, André ;
in Cellular and Molecular Life Sciences : CMLS (1998), 54(4), 363-71
How a conformationally disordered polypeptide chain rapidly and efficiently achieves its well-defined native structure is still a major question in modern structural biology. Although much progress has ... [more ▼]
How a conformationally disordered polypeptide chain rapidly and efficiently achieves its well-defined native structure is still a major question in modern structural biology. Although much progress has been made towards rationalizing the principles of protein structure and dynamics, the mechanism of the folding process and the determinants of the final fold are not yet known in any detail. One protein for which folding has been studied in great detail by a combination of diverse techniques is hen lysozyme. In this article we review the present state of our knowledge of the folding process of this enzyme and focus in particular on recent experiments to probe some of its specific features. These results are then discussed in the context of the 'new view' of protein folding based on energy surfaces and landscapes. It is shown that a schematic energy surface for lysozyme folding, which is broadly consistent with our experimental data, begins to provide a unified model for protein folding through which experimental and theoretical ideas can be brought together. [less ▲]Detailed reference viewed: 33 (9 ULg)
"La folie heureuse" : à propos d'un passage d'Horace (Épîtres II, 2, v. 128-140)
in Filiber, Carine (Ed.) Vertiges de la folie. Catalogue de l'exposition (Musée de la Vie Wallonne, Liège, 30/03-19/08/2012) (2012)Detailed reference viewed: 28 (7 ULg)
Foliicolous lichens from Madeira, with the description of a new genus and two new species and a world-wide key to foliicolous Fellhanera
in Lichenologist (1996), 28Detailed reference viewed: 9 (0 ULg)
Foliicolous lichens from Southeastern United States
in Bryologist (1979), 82Detailed reference viewed: 10 (0 ULg)
Foliicolous lichens: ecological and chorological data
in Botanical Journal of the Linnean Society (1986), 100Detailed reference viewed: 12 (0 ULg)
Folinic acid treatment for schizophrenia associated with folate receptor autoantibodies.
RAMAEKERS, Vincent ; ; et al
in Molecular genetics and metabolism (2014), 113(4), 307-14
BACKGROUND: Auto-antibodies against folate receptor alpha (FRalpha) at the choroid plexus that block N(5)-methyltetrahydrofolate (MTHF) transfer to the brain were identified in catatonic schizophrenia ... [more ▼]
BACKGROUND: Auto-antibodies against folate receptor alpha (FRalpha) at the choroid plexus that block N(5)-methyltetrahydrofolate (MTHF) transfer to the brain were identified in catatonic schizophrenia. Acoustic hallucinations disappeared following folinic acid treatment. Folate transport to the CNS prevents homocysteine accumulation and delivers one-carbon units for methyl-transfer reactions and synthesis of purines. The guanosine derivative tetrahydrobiopterin acts as common co-factor for the enzymes producing dopamine, serotonin and nitric oxide. METHODS: Our study selected patients with schizophrenia unresponsive to conventional treatment. Serum from these patients with normal plasma homocysteine, folate and vitamin B12 was tested for FR autoantibodies of the blocking type on serial samples each week. Spinal fluid was analyzed for MTHF and the metabolites of pterins, dopamine and serotonin. The clinical response to folinic acid treatment was evaluated. RESULTS: Fifteen of 18 patients (83.3%) had positive serum FR auto-antibodies compared to only 1 in 30 controls (3.3%) (chi(2)=21.6; p<0.0001). FRalpha antibody titers in patients fluctuated over time varying between negative and high titers, modulating folate flux to the CNS, which explained low CSF folate values in 6 and normal values in 7 patients. The mean+/-SD for CSF MTHF was diminished compared to previously established controls (t-test: 3.90; p=0.0002). A positive linear correlation existed between CSF MTHF and biopterin levels. CSF dopamine and serotonin metabolites were low or in the lower normal range. Administration of folinic acid (0.3-1mg/kg/day) to 7 participating patients during at least six months resulted in clinical improvement. CONCLUSION: Assessment of FR auto-antibodies in serum is recommended for schizophrenic patients. Clinical negative or positive symptoms are speculated to be influenced by the level and evolution of FRalpha antibody titers which determine folate flux to the brain with up- or down-regulation of brain folate intermediates linked to metabolic processes affecting homocysteine levels, synthesis of tetrahydrobiopterin and neurotransmitters. Folinic acid intervention appears to stabilize the disease process. [less ▲]Detailed reference viewed: 40 (3 ULg)
Folipidine, a new type quinoline alkaloid from plants of the Haplophyllum genus
; ; et al
in Chemistry of Natural Compounds (2005), 41(1, JAN-FEB), 60-64
The new quinoline alkaloid folipidine, the structure of which was established by chemical transformations and spectral data (UV, IR, mass, NMR) using APT 2D H-1-H-1 COSY, NOESY, and H-1-(13)CHSQC, HMBC ... [more ▼]
The new quinoline alkaloid folipidine, the structure of which was established by chemical transformations and spectral data (UV, IR, mass, NMR) using APT 2D H-1-H-1 COSY, NOESY, and H-1-(13)CHSQC, HMBC, was isolated from two plants of the Haplophyllum mints. Folipidine is the first representative of a new type of quinoline alkaloids that contain a heteroaromatic skeleton of [3,4-b]conjugated pyrrole and quinoline fragments. The total alkaloids of these plants exhibit antitumor activity. Folipidine does not possess such activity. [less ▲]Detailed reference viewed: 36 (0 ULg)
Follicle Stimulating Hormone -Secreting Pituitary adenomas
Beckers, Albert ; Stevenaert, Achille ; et al
in Journal of Clinical Endocrinology and Metabolism (1985), 61(3), 525-528
This retrospective study concerns 40 patients with an apparently nonsecretory pituitary adenoma who were operated on during an 11-yr period from 1971 to 1981. Among them, 6 men had elevated serum FSH ... [more ▼]
This retrospective study concerns 40 patients with an apparently nonsecretory pituitary adenoma who were operated on during an 11-yr period from 1971 to 1981. Among them, 6 men had elevated serum FSH levels. LH levels were normal in 5 and slightly elevated in 1. Testosterone levels were low in 2 patients and within normal limits in 2 others. Sexual impotency had developed from 6 months to 1 yr before surgery in all patients. Primary hypogonadism could be eliminated on clinical grounds (recent onset of hypogonadism, previous fertility of 5 of the 6, and postoperative improvement). After transsphenoidal adenomectomy, FSH levels returned to normal values in all, and clinical recovery occurred in most patients. Tumor tissue obtained at operation stained positively for the gonadotropins, but was negative for other pituitary hormones in all patients. The most probable explanation for these findings was that the tumors were responsible for the elevated FSH secretion. This explanation is supported by the immunocytochemical identification of gonadotropin-containing cells in the tumors. We conclude that these 6 men frm a series of 40 patients who presented with pituitary tumor but no GH, PRL, or ACTH hypersecretion had primary gonadotropinomas. [less ▲]Detailed reference viewed: 17 (0 ULg)
A follicle-stimulating-hormone secreting pituitary adenoma treated with long acting repeatable bromocriptine.
; Beckers, Albert ;
in Journal of Endocrinological Investigation (1990), 13Detailed reference viewed: 9 (0 ULg)
Follicular dendritic cells control engulfment of apoptotic bodies by secreting Mfge8.
; ; Heinen, Ernst et al
in Journal of Experimental Medicine (2008), 205(6), 1293-302
The secreted phosphatidylserine-binding protein milk fat globule epidermal growth factor 8 (Mfge8) mediates engulfment of apoptotic germinal center B cells by tingible-body macrophages (TBMphis ... [more ▼]
The secreted phosphatidylserine-binding protein milk fat globule epidermal growth factor 8 (Mfge8) mediates engulfment of apoptotic germinal center B cells by tingible-body macrophages (TBMphis). Impairment of this process can contribute to autoimmunity. We show that Mfge8 is identical to the mouse follicular dendritic cell (FDC) marker FDC-M1. In bone-marrow chimeras between wild-type and Mfge8(-/-) mice, all splenic Mfge8 was derived from FDCs rather than TBMphis. However, Mfge8(-/-) TBMphis acquired and displayed Mfge8 only when embedded in Mfge8(+/+) stroma, or when situated in lymph nodes draining exogenous recombinant Mfge8. These findings indicate a licensing role for FDCs in TBMphi-mediated removal of excess B cells. Lymphotoxin-deficient mice lacked FDCs and splenic Mfge8, and suffer from autoimmunity similar to Mfge8(-/-) mice. Hence, FDCs facilitate TBMphi-mediated corpse removal, and their malfunction may be involved in autoimmunity. [less ▲]Detailed reference viewed: 49 (6 ULg)
Follicular Dendritic Cells Do Not Produce Tnf-Alpha nor its Receptor
; ; et al
in Advances in Experimental Medicine and Biology (1993), 329Detailed reference viewed: 14 (0 ULg)
Follicular dendritic cells in lymph nodes after x-irradiation.
; Heinen, Ernst ; Radoux, Dominique et al
in International Journal of Radiation Biology and Related Studies in Physics, Chemistry, and Medicine (1982), 42(2), 121-30
Follicular dendritic cells (FDC), non lymphoid cells present in lymph follicles, are characterized by numerous cytoplasmic processes retaining antigen-antibody complexes. Their origin, nature and function ... [more ▼]
Follicular dendritic cells (FDC), non lymphoid cells present in lymph follicles, are characterized by numerous cytoplasmic processes retaining antigen-antibody complexes. Their origin, nature and function are unknown. Mice inguinal lymph nodes after 4.5 or 7.5 Gy X-irradiation were depleted of lymphoid cells. Ultrastructural observations during the first few days post-irradiation show that FDC are unaltered and possess dendritic processes enveloping dense material. Furthermore, they show intense metabolic activity. A lamina densa, never observed so well-developed in other lymph node cells, was detected around the nuclear envelope. The localization of junctions between FDC was analysed. FDC preserve their typical cytoplasmic processes even if lymphoid cells are rare. The latter thus seem not to be responsible for the maintenance of FDC integrity or their development. The possible role of this for antibody production is discussed. Irradiated lymph nodes of lymphoid cells are highly convenient for studying FDC. Isolation of FDC from irradiated lymph organs would seem to be possible. [less ▲]Detailed reference viewed: 23 (0 ULg)
The follicular dendritic cells in normal and pathological conditions
Book published by Springer (1995)Detailed reference viewed: 9 (0 ULg)