Anna Jansson
Karolinska Institutet
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Featured researches published by Anna Jansson.
Acta Paediatrica | 2007
Anna Jansson; Tönu Saartok; Suzanne Werner; Per Renström
Aim: To evaluate general joint laxity in growing children with the aim of determining a cut‐off point for joint hypermobility. Methods: Using the Beighton score, 1845 children from 48 geographically randomly selected schools were evaluated for general joint laxity. The Beighton score evaluates the ability to perform a selection of manoeuvres involving five different joints. The children made up three different age groups (9, 12 and 15 y old) at the time of testing and were approximately equally distributed concerning age and gender in all groups. Results: There were significant differences in Beighton scores concerning both age and gender. Whereas boys presented significant decreases in the degree of general joint laxity with increasing age, girls presented the highest degree of general joint laxity at the age of 15. At all ages girls had a higher degree of general joint laxity
The EMBO Journal | 2004
Azmiri Sultana; Anna Jansson; Ji-Shu Wang; Jarmo Niemi; Pekka Mäntsälä; Gunter Schneider
SnoaL belongs to a family of small polyketide cyclases, which catalyse ring closure steps in the biosynthesis of polyketide antibiotics produced in Streptomyces. Several of these antibiotics are among the most used anti‐cancer drugs currently in use. The crystal structure of SnoaL, involved in nogalamycin biosynthesis, with a bound product, has been determined to 1.35 Å resolution. The fold of the subunit can be described as a distorted α+β barrel, and the ligand is bound in the hydrophobic interior of the barrel. The 3D structure and site‐directed mutagenesis experiments reveal that the mechanism of the intramolecular aldol condensation catalysed by SnoaL is different from that of the classical aldolases, which employ covalent Schiff base formation or a metal ion cofactor. The invariant residue Asp121 acts as an acid/base catalyst during the reaction. Stabilisation of the enol(ate) intermediate is mainly achieved by the delocalisation of the electron pair over the extended π system of the substrate. These polyketide cyclases thus form of family of enzymes with a unique catalytic strategy for aldol condensation.
Pain | 2008
Gunilla Brun Sundblad; Anna Jansson; Tönu Saartok; Per Renström; Lars-Magnus Engström
&NA; The aim of this longitudinal study was to assess changes with age regarding prevalence of pain and perceived health in a student population, as well as change over time at grade level. Pain included frequency of headache, abdominal, and musculoskeletal pain and perceived health included problems sleeping and/or if they often felt tired, lonely, and sad. If gender, age (grade level), stress, physically activity were related to pain and health complaints were tested with multivariate logistic regression analysis. The students (n = 1908) came from randomly selected schools throughout Sweden and attended grades 3, 6 and 9 (ages 9, 12 and 15 at the onset of the year) in 2001. Three years later, 67% (n = 1276) of the same students answered a questionnaire that was constructed for the purpose of the studies. The responses given by the same students showed that girls’ complaints of pain and perceived health increased with age and boys decreased. Over half (56%) of the girls and two‐thirds (67%) of the boys reported no frequent complaints either year. At grade level most variables were rated the same as three years earlier by the same age group. Stress was significantly related to pain and health complaints for girls and the risk of complaints, as calculated with odds ratio, was most evident for students who were characterized as being physically inactive in 2001 and remained inactive three years later. Jointly, significant predictors, such as stress, being physically inactive, gender and grade level, explained 8–20% of the frequent complaints.
Scandinavian Journal of Medicine & Science in Sports | 2005
Anna Jansson; Tönu Saartok; Suzanne Werner; Per Renström
The aim of the study was to evaluate differences between competitive swimmers and a reference group of school children concerning general joint laxity, laxity of the glenohumeral joint and range of motion in the shoulder. Materials and methods. Competitive swimmers (n=120) were compared with references consisting of age and gender matched school children (n=1277). General joint laxity was evaluated with the Beighton score. Anterior glenohumeral laxity was assessed according to the drawer test, and inferior glenohumeral laxity according to the sulcus test. Shoulder rotation was measured with a goniometer.
Journal of Biological Chemistry | 2003
Anna Jansson; Jarmo Niemi; Pekka Mäntsälä; Günter Schneider
Aclacinomycin methylesterase (RdmC) is one of the tailoring enzymes that modify the aklavinone skeleton in the biosynthesis of anthracyclines in Streptomyces species. The crystal structures of this enzyme from Streptomyces purpurascens in complex with the product analogues 10-decarboxymethylaclacinomycin T and 10-decarboxymethylaclacinomycin A were determined to nominal resolutions of 1.45 and 1.95 Å, respectively. RdmC is built up of two domains. The larger α/β domain shows the common α/β hydrolase fold, whereas the smaller domain is α-helical. The active site and substrate binding pocket are located at the interface between the two domains. Decarboxymethylaclacinomycin T and decarboxymethylaclacinomycin A bind close to the catalytic triad (Ser102-His276-Asp248) in a hydrophobic pocket, with the sugar moieties located at the surface of the enzyme. The binding of the ligands is dominated by hydrophobic interactions, and specificity appears to be controlled mainly by the shape of the binding pocket rather than through specific hydrogen bonds. Mechanistic key features consistent with the structure of complexes of RdmC with product analogues are Ser102 acting as nucleophile and transition state stabilization by an oxyanion hole formed by the backbone amides of residues Gly32 and Met103.
Acta Crystallographica Section D-biological Crystallography | 2004
Azmiri Sultana; Anna Jansson; Jarmo Niemi; Pekka Mäntsälä; Gunter Schneider
Nogalonic acid methyl ester cyclase (SnoaL) catalyzes the last ring-closure step in the biosynthesis of the polyketide antibiotic nogalamycin. Crystals of a complex of SnoaL with the substrate nogalonic acid methyl ester have been obtained using PEG 4000 as precipitant. The crystals are orthorhombic, space group I222, with unit-cell parameters a = 69.1, b = 72.0, c = 65.4 angstroms. They diffract to 1.35 angstroms resolution using synchrotron radiation. A Matthews coefficient of 2.0 angstroms3 Da(-1) suggests one subunit in the asymmetric unit. Diffraction data for an isomorphous uranium derivative were collected and a difference Patterson map showed strong peaks which allowed determination of the position of the uranium ions.
Acta Crystallographica Section D-biological Crystallography | 2003
Anna Jansson; Jarmo Niemi; Pekka Mäntsälä; Günter Schneider
Two enzymes participating in the biosynthesis of anthracyclines in Streptomyces purpurascens, aclacinomycin-10-methyl esterase (RdmC) and aclacinomycin-10-hydroxylase (RdmB), have been crystallized. RdmB is a S-adenosyl-methionine-dependent hydroxylase and RdmC hydrolyses the carboxymethyl group of the aglycone skeleton of aclacinomycin. Crystals of RdmB obtained in the presence of S-adenosyl-L-methionine were orthorhombic, space group C222(1), with unit-cell parameters a = 63.2, b = 92.2, c = 115.3 A; diffraction data were collected to 2.1 A resolution. RdmC was crystallized as a complex with the substrate, aclacinomycin T. These crystals diffracted to 1.45 A resolution and belonged to space group P2(1), with unit-cell parameters a = 38.2, b = 84.7, c = 44.3 A, beta = 99.9 degrees.
Journal of Biological Chemistry | 2017
Dan Chen; Anna Jansson; Daniel Sim; Andreas Larsson; Pär Nordlund
Thymidylate synthase (TS) is the sole enzyme responsible for de novo biosynthesis of thymidylate (TMP) and is essential for cell proliferation and survival. Inhibition of human TS (hTS) has been extensively investigated for cancer chemotherapy, but several aspects of its activity and regulation are still uncertain. In this study, we performed comprehensive structural and biophysical studies of hTS using crystallography and thermal shift assay and provided the first detailed structural information on the conformational changes induced by ligand binding to the hTS active site. We found that upon binding of the antifolate agents raltitrexed and nolatrexed, the two insert regions in hTS, the functions of which are unclear, undergo positional shifts toward the catalytic center. We investigated the inactive conformation of hTS and found that the two insert regions are also involved in the conformational transition between the active and inactive state of hTS. Moreover, we identified a ligand-binding site in the dimer interface, suggesting that the cavity in the dimer interface could serve as an allosteric site of hTS to regulate the conformational switching between the active and inactive states. On the basis of these findings, we propose a regulatory mechanism of hTS activity that involves allosteric regulation of interactions of hTS with its own mRNA depending on cellular demands for TMP.
Journal of Biological Chemistry | 2004
Anna Jansson; Hanna Koskiniemi; Pekka Mäntsälä; Jarmo Niemi; Gunter Schneider
Journal of Molecular Biology | 2003
Anna Jansson; Jarmo Niemi; Ylva Lindqvist; Pekka Mäntsälä; Gunter Schneider