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- Ek, Pia, et al.
(författare)
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Phosphohistidine phosphatase 1 (PHPT1) also dephosphorylates phospholysine of chemically phosphorylated histone H1 and polylysine
- 2015
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Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 120:1, s. 20-27
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Tidskriftsartikel (refereegranskat)abstract
- Background. Phosphohistidine phosphatase 1 (PHPT1), also named protein histidine phosphatase (PHP), is a eukaryotic enzyme dephosphorylating proteins and peptides that are phosphorylated on a histidine residue. A preliminary finding that histone H1, which lacks histidine, was phosphorylated by phosphoramidate and dephosphorylated by PHPT1 prompted the present investigation. Methods. Histone H1 and polylysine were phosphorylated at a low concentration (3.9 mM) of phosphoramidate. Their dephosphorylation by recombinant human PHPT1 was investigated by using a DEAE-Sepharose spin column technique earlier developed by us for studies on basic phosphoproteins and phosphopeptides. Determination of protein-bound, acid-labile phosphate was performed by a malachite green method. Mass spectrometry (MS) was used to investigate the occurrence of N-epsilon-phospholysine residues in a phosphorylated histone H 1.2 preparation, and to measure the activity of PHPT1 against free N-omega-phosphoarginine. Results. Histone H1.2, which lacks histidine, was phosphorylated by phosphoramidate on several lysine residues, as shown by MS. PHPT1 was shown to dephosphorylate phosphohistone H1 at a rate similar to that previously described for the dephosphorylation of phosphohistidine-containing peptides. In addition, phosphopolylysine was an equally good substrate for PHPT1. However, no dephosphorylation of free phosphoarginine by PHPT1 could be detected. Conclusion. The finding that PHPT1 can dephosphorylate phospholysine in chemically phosphorylated histone H1 and polylysine demonstrates a broader specificity for this enzyme than known so far.
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| 3. |
- Adolfsson, Päivi, 1956-, et al.
(författare)
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Dietitians’ challenges when consulting to adults with intellectual disabilities
- 2019
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Ingår i: Tizard Learning Disability Review. - 1359-5474 .- 2042-8782. ; 24:4, s. 153-162
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The purpose of this paper is to investigate registered dietitians' (RDs) experiences in consulting to adults with intellectual disabilities (ID) in Sweden.Design/methodology/approach: A descriptive study using a study-specific web-based questionnaire was administered, comprising both multiple-choice questions with a space for comments and open-ended questions. The open-ended answers and comments from 53 respondents were analysed with systematic text condensation.Findings: Four categories were identified: RDs' experiences from the first meeting; explanations for late initial contact; the actions taken by RDs; and necessary measures for more sustainable nutrition care. Ten sub-categories described the challenges that RDs experience in more detail.Practical implications: It is necessary to provide adults with ID and their supporting staff with individually tailored nutritional information. Individuals with ID must be actively involved in lifestyle changes that affect their everyday life. The RD must be included in the interdisciplinary team supporting adults with ID. If a new practice is to be implemented, it should be compatible with the existing values of adults with ID and their staff and must be feasible to implement in the everyday life of the individual.Originality/value: This paper identified several barriers that should be overcome in relation to the preparation of RDs for consultation with adults with ID about nutritional health issues. A systematic structure, knowledge about nutrition and knowledge about adults with ID and their living situations are needed. An assessment instrument may meet health promotion needs and facilitate longitudinal follow-ups of nutritional problems.
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| 4. |
- Hellström, Pia, 1960-
(författare)
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Fenton Pre-treatment of a Birch Kraft Pulp for MFC preparation
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The potential to use acidic hydrogen peroxide in the presence of ferrous ions (Fenton’s reagent) as a pre-treatment when producing microfibrillar cellulose (MFC) from a fully bleached birch (Betula verucosa) kraft pulp was investigated and the properties of the produced MFC was compared to the properties of a MFC produced with enzymatic pre-treatment with a monocomponent endoglucanase (FiberCare® R). The mechanical treatment to MFC was performed in a laboratory colloid mill or in a pilot high-pressure homogeniser and the pre-treated pulps as well as the produced MFCs were chemically and morphologically characterised. Additionally, the MFCs produced in the colloid mill were evaluated as strength enhancers in test sheets representing the middle ply of paperboard.From the chemical characterisation, it was concluded that the Fenton pre-treatment caused a decrease in the degree of polymerisation (DP) and an increase in both carboxyl- and carbonyl groups. The increase in carbonyl groups could not be explained by the formation of new reducing end groups due to depolymerisation which indicates that carbonyl groups are introduced along the cellulose chain. The enzymatic pre-treatment as performed in this study caused less impact on the cellulosic material, i.e. resulted in a pulp with a higher DP and a much lower amount of carbonyl- and carboxylic groups compared with the Fenton pre-treated pulps. In the subsequent mechanical treatment in a colloid mill, the Fenton pre-treated pulps were easier to process mechanically i.e. reached a higher specific surface area and a higher surface charge at a given mechanical treatment time compared to enzymatic pre-treated pulps and pulps not subjected to any pre-treatment. These findings were confirmed when MFCs were produced by homogenisation at high pressure in multiple passes; the birch kraft pulp was either pre-treated with Fenton’s reagent or the combined mechanic and enzymatic pre-treatment methodology used at the Centre Technique du Papier (CTP, France). By size fractionation, rheological measurements and scanning electron microscopy, it was revealed that Fenton pre-treatment resulted in MFC suspension containing a significantly higher proportion of small sized material (< 0.2 mm).When the MFCs were evaluated as strength enhancers in test sheets produced from a furnish consisting of a spruce (Picea abies) chemithermomechanical pulp, MFC and a retention system containing cationic starch and an anionic silica sol, Fenton pre-treated MFCs increased the strength properties more than the enzymatic pre-treated MFCs. Addition of 5 wt% Fenton pre-treated MFC resulted in an increase in z-directional strength of about 50%, an increase in tensile stiffness index of about 25% and an increase in tensile index of 35% compared to test sheets prepared without MFC addition.
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