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71.
Pratibha Kumari Lukas Frey Alexander Sobol Nils-Alexander Lakomek Roland Riek 《Journal of biomolecular NMR》2018,72(3-4):125-137
15N R2 relaxation measurements are key for the elucidation of the dynamics of both folded and intrinsically disordered proteins (IDPs). Here we show, on the example of the intrinsically disordered protein α-synuclein and the folded domain PDZ2, that at physiological pH and near physiological temperatures amide—water exchange can severely skew Hahn-echo based 15N R2 relaxation measurements as well as low frequency data points in CPMG relaxation dispersion experiments. The nature thereof is the solvent exchange with deuterium in the sample buffer, which modulates the 15N chemical shift tensor via the deuterium isotope effect, adding to the apparent relaxation decay which leads to systematic errors in the relaxation data. This results in an artificial increase of the measured apparent 15N R2 rate constants—which should not be mistaken with protein inherent chemical exchange contributions, Rex, to 15N R2. For measurements of 15N R2 rate constants of IDPs and folded proteins at physiological temperatures and pH, we recommend therefore the use of a very low D2O molar fraction in the sample buffer, as low as 1%, or the use of an external D2O reference along with a modified 15N R2 Hahn-echo based experiment. This combination allows for the measurement of Rex contributions to 15N R2 originating from conformational exchange in a time window from µs to ms. 相似文献
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Pepsinogen polymorphism in the Indian population and its association with duodenal ulcer 总被引:1,自引:0,他引:1
A. Venkateshwari A. Vidyasagar Rupender Prasad Bajrang Pratap N. Pratibha 《Human genetics》1997,101(2):201-204
To date, there have been few studies on pepsinogen polymorphism. The present study examines the polymorphism of pepsinogen
by PAGE in 155 duodenal ulcer cases and 92 control subjects. The Indian population presents a higher frequency of the B phenotype
(associated with absence of the pg 5 fraction) and the C haplotype compared to other populations. Heterozygotes, in particular
AC phenotypic individuals, are found to be associated significantly with the disease compared to control subjects. All the
genes of the multigene complex controlling pepsinogen polymorphism seem to be interacting, thereby leading to such an association.
Thus, studies at the gene level may be helpful in explaining the genetic etiology and heterogeneity of duodenal ulcer disease.
Received: 15 August 1996 / Accepted: 18 July 1997 相似文献
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Nidhi Verma Om Prakash Narayan Durga Prasad Abhimanyu Jogawat Sneh Lata Panwar Meenakshi Dua Atul Kumar Johri 《Environmental microbiology》2022,24(2):689-706
Iron (Fe) is a micronutrient required for plant growth and development; however, most Fe forms in soil are not readily available to plants, resulting in low Fe contents in plants and, thereby, causing Fe deficiency in humans. Biofortification through plant-fungal co-cultivation might be a sustainable approach to increase crop Fe contents. Therefore, we aimed to examine the role of a Piriformospora indica Fe transporter on rice Fe uptake under low Fe conditions. A high-affinity Fe transporter (PiFTR) from P. indica was identified and functionally characterized. PiFTR fulfilled all criteria expected of a functional Fe transporter under Fe-limited conditions. Additionally, PiFTR expression was induced when P. indica was grown under low Fe conditions, and PiFTR complemented a yeast mutant lacking Fe transport. A knockdown (KD) P. indica strain was created via RNA interference to understand the physiological role of PiFTR. We observed that the KD-PiFTR-P. indica strain transported a significantly lower amount of Fe to colonized rice (Oryza sativa) than the wild type (WT) P. indica. WT P. indica-colonized rice plants were healthier and performed significantly better than KD-PiFTR-P. indica-colonized rice plants. Our study offers potential avenues for an agronomically sound amelioration of plant growth in low Fe environments. 相似文献
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P Jalmi P Bodke S Wahidullah S Raghukumar 《World journal of microbiology & biotechnology》2012,28(2):505-512
Melanins are commonly produced by bacteria, fungi, plants and animals, where they play a role in many biological functions.
They protect organisms against UV and ionizing radiations. Their potential applications in biotechnological industries such
as cosmetics and paints, where UV protection is required, are hampered by the lack of suitable organisms or methods to produce
them abundantly. We report here the production of high amounts of extracellular melanin by the fungus Gliocephalotrichum simplex in cultures supplemented with tyrosine. Their typical UV-absorbance, as well as i.r., 13C solid-state and 1H NMR spectra indicated that the melanin is a eumelanin, being a copolymer of dihydroxyindole carboxylic acid and dihydroxyindole,
associated with some carbohydrates and proteinaceous matter. Optimal culture conditions established by a Plackett-Burman experiment,
followed by a full factorial experiment based on tyrosine and peptone yielded a maximum of up to 6.6 g melanin l−1. The high yields of extracellular melanin from G. simplex enables its use in biotechnology. 相似文献
80.
Since endo-symbiotic events occur, all genes of mitochondrial aminoacyl tRNA synthetase (AARS) were lost or transferred from ancestral mitochondrial genome into the nucleus. The canonical pattern is that both cytosolic and mitochondrial AARSs coexist in the nuclear genome. In the present scenario all mitochondrial AARSs are nucleus-encoded, synthesized on cytosolic ribosomes and post-translationally imported from the cytosol into the mitochondria in eukaryotic cell. The site-based discrimination between similar types of enzymes is very challenging because they have almost same physico-chemical properties. It is very important to predict the sub-cellular location of AARSs, to understand the mitochondrial protein synthesis. We have analyzed and optimized the distinguishable patterns between cytosolic and mitochondrial AARSs. Firstly, support vector machines (SVM)-based modules have been developed using amino acid and dipeptide compositions and achieved Mathews correlation coefficient (MCC) of 0.82 and 0.73, respectively. Secondly, we have developed SVM modules using position-specific scoring matrix and achieved the maximum MCC of 0.78. Thirdly, we developed SVM modules using N-terminal, intermediate residues, C-terminal and split amino acid composition (SAAC) and achieved MCC of 0.82, 0.70, 0.39 and 0.86, respectively. Finally, a SVM module was developed using selected attributes of split amino acid composition (SA-SAAC) approach and achieved MCC of 0.92 with an accuracy of 96.00%. All modules were trained and tested on a non-redundant data set and evaluated using fivefold cross-validation technique. On the independent data sets, SA-SAAC based prediction model achieved MCC of 0.95 with an accuracy of 97.77%. The web-server 'MARSpred' based on above study is available at http://www.imtech.res.in/raghava/marspred/. 相似文献