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Sørensen SO, Larsen KT, Høy TV, Hansen ABG, Jago R, Kristensen PL, Toftager M, Grøntved A, Gejl AK. Study protocol for the Screen-Free Time with Friends Feasibility Trial. Pilot Feasibility Stud 2024; 10:33. [PMID: 38374084 PMCID: PMC10875870 DOI: 10.1186/s40814-024-01462-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 02/06/2024] [Indexed: 02/21/2024] Open
Abstract
BACKGROUND Children are spending less leisure time with their friends in person and an increasing amount of time with digital screens. These changes may negatively affect children's physical and mental health. The Screen-Free Time with Friends Feasibility Trial will test the feasibility, including acceptability and compliance, of an intervention designed to reduce screen media usage and encourage physical interaction with friends during leisure time in 9-11-year-old children. METHODS A non-randomized single-group feasibility trial will be conducted from March to October 2023 including approximately 75 children (aged 9-11 years) and 75 parents (at least 1 per child) from 3 different schools recruited from 3 different municipalities in Denmark. The Screen-Free Time with Friends intervention is a multicomponent intervention targeting families, afterschool clubs, and local communities. It has been developed using a systematic process guided by the Medical Research Council UK's framework for developing and evaluating complex interventions. With a systems perspective in mind, the intervention and implementation approach has been designed to facilitate adaptation to the specific needs of diverse local communities while maintaining the core components of the intervention. Feasibility and acceptability of the intervention will be assessed during the intervention using process evaluation inspired by the RE-AIM framework including questionnaires and interviews with the municipality project managers, research team members, local ambassadors and stakeholders, parents and school, and afterschool club personnel. In addition, participation, recruitment, retention rate, and compliance to the outcome measurements will be investigated and presented. DISCUSSION The trial will investigate the feasibility and acceptability of the Screen-Free Time with Friends intervention, the recruitment strategy, and the planned outcome measurements. This feasibility study will investigate necessary refinements before the implementation of the intervention program in a larger cluster randomized controlled trial to evaluate its impact. TRIAL REGISTRATION CLINICALTRIALS gov, ID: NCT05480085. Registered 29 July 2022. https://clinicaltrials.gov/ct2/show/NCT05480085?cond=Screen+free+time+with+friends&draw=2&rank=1.
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Affiliation(s)
- Sarah Overgaard Sørensen
- Research Unit for Exercise Epidemiology, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
| | - Kristian Traberg Larsen
- Research Unit for Exercise Epidemiology, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Teresa Victoria Høy
- National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark
| | | | - Russell Jago
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
- NIHR Bristol Biomedical Research Centre, University Hospitals Bristol and Weston NHS Foundation Trust and University of Bristol, Bristol, UK
| | - Peter Lund Kristensen
- Research Unit for Exercise Epidemiology, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Mette Toftager
- Research Unit for Active Living, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Anders Grøntved
- Research Unit for Exercise Epidemiology, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Anne Kær Gejl
- Research Unit for Exercise Epidemiology, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
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Sørensen SO, Gejl AK, Pedersen J, Rasmussen MG, Olesen LG, Kristensen PL, Grøntved A. Recreational screen media use among Danish children aged 6-11 years: influence of parental screen media habits and attitudes. Scand J Public Health 2023; 51:1173-1181. [PMID: 35708326 DOI: 10.1177/14034948221103463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AIMS Little is known about the influence of parents' screen media habits and attitudes towards screen media on children's screen use. We investigated associations of parental screen use, their smartphone addiction and screen media attitudes, with children's recreational screen use. METHODS This study was based on a population-based cross-sectional survey sent between May 2019 and November 2020 to a random sample of 6820 Danish parent-child dyads who answered questions regarding their screen media habits. Children were 6-11 years of age and had to reside with the parent. Multivariable adjusted regression analyses were conducted (in October 2021) separately for screen media use on weekdays and weekend days. RESULTS The analyses included 5437 parents (41.0 years, 67.6% girls) and 5437 children (8.9 years, 48.2% girls). The adjusted relative odds of excessive amounts of screen use of children (>3 hours/weekday and >4 hours/weekend day) was 5.8 (95% confidence interval (CI) 4.6; 7.3) on weekdays and 7.2 (95% CI 5.9; 8.8) on weekend days comparing the fourth and first quartile of parental screen use. Children of parents in the fourth quartile of parental screen use had 2.1 (95% CI 1.7; 2.5) and 2.5 (95% CI 2.2; 3.0) greater odds of screen use before bedtime on all week and weekend days, respectively. Children of parents who had a positive attitude towards their child's screen use or were at high risk of smartphone addiction had significantly higher screen use and more frequent problematic screen use. CONCLUSIONS Parent's screen media habits and attitudes were strongly associated with their children's recreational screen use.
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Affiliation(s)
- Sarah Overgaard Sørensen
- Department of Sports Science and Clinical Biomechanics Research Unit for Exercise Epidemiology, University of Southern Denmark, Odense, Denmark
| | - Anne Kær Gejl
- Department of Sports Science and Clinical Biomechanics Research Unit for Exercise Epidemiology, University of Southern Denmark, Odense, Denmark
| | - Jesper Pedersen
- Department of Sports Science and Clinical Biomechanics Research Unit for Exercise Epidemiology, University of Southern Denmark, Odense, Denmark
| | - Martin Gillies Rasmussen
- Department of Sports Science and Clinical Biomechanics Research Unit for Exercise Epidemiology, University of Southern Denmark, Odense, Denmark
| | - Line Grønholt Olesen
- Department of Sports Science and Clinical Biomechanics Research Unit for Exercise Epidemiology, University of Southern Denmark, Odense, Denmark
| | - Peter Lund Kristensen
- Department of Sports Science and Clinical Biomechanics Research Unit for Exercise Epidemiology, University of Southern Denmark, Odense, Denmark
| | - Anders Grøntved
- Department of Sports Science and Clinical Biomechanics Research Unit for Exercise Epidemiology, University of Southern Denmark, Odense, Denmark
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Pedersen J, Rasmussen MGB, Sørensen SO, Mortensen SR, Olesen LG, Brage S, Kristensen PL, Puterman E, Grøntved A. Effects of limiting digital screen use on well-being, mood, and biomarkers of stress in adults. Npj Ment Health Res 2022; 1:14. [PMID: 37521498 PMCID: PMC9554843 DOI: 10.1038/s44184-022-00015-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 09/29/2022] [Indexed: 11/07/2022]
Abstract
Studies have linked higher digital screen use with poorer mental health. However, there is limited experimental evidence to suggest a causal relationship. In this trial, we aimed to investigate the effects of limiting recreational digital screen use on mental well-being, mood, and biomarkers of stress in healthy young and middle-aged adults. We randomly allocated 89 families (including 164 adults) to participate in an extensive screen media reduction intervention or control. Participants in the intervention group were instructed to decrease their recreational screen use to less than 3 hours/week/person. Intervention compliance was assessed using applications and tv-monitors. Overall subjective mental well-being and mood, and collected daily biomarkers of stress (salivary cortisol and cortisone) was assessed at baseline and 2-week follow-up. Reducing recreational digital screen use resulted in significantly improved self-reported well-being and mood in adults allocated to the intervention compared to control. We observed no intervention effects for biomarkers of stress. (ClinicalTrials.gov: NCT04098913, 23/09/2019).
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Affiliation(s)
- Jesper Pedersen
- Department of Sports Science and Clinical Biomechanics, Research unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
| | - Martin Gillies Banke Rasmussen
- Department of Sports Science and Clinical Biomechanics, Research unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
- Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark
| | - Sarah Overgaard Sørensen
- Department of Sports Science and Clinical Biomechanics, Research unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
| | - Sofie Rath Mortensen
- Department of Sports Science and Clinical Biomechanics, Research unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
- Research unit PROgrez, Department of Physiotherapy and Occupational Therapy, Naestved-Slagelse-Ringsted Hospitals, Region Zealand, Denmark
| | - Line Grønholt Olesen
- Department of Sports Science and Clinical Biomechanics, Research unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
| | - Søren Brage
- Department of Sports Science and Clinical Biomechanics, Research unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
- MRC Epidemiology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Peter Lund Kristensen
- Department of Sports Science and Clinical Biomechanics, Research unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
| | - Eli Puterman
- Fitness, Aging, and Stress lab, School of Kinesiology, University of British Columbia, Vancouver, BC Canada
| | - Anders Grøntved
- Department of Sports Science and Clinical Biomechanics, Research unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
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Pedersen J, Rasmussen MGB, Sørensen SO, Mortensen SR, Olesen LG, Brønd JC, Brage S, Kristensen PL, Grøntved A. Effects of Limiting Recreational Screen Media Use on Physical Activity and Sleep in Families With Children: A Cluster Randomized Clinical Trial. JAMA Pediatr 2022; 176:741-749. [PMID: 35604678 PMCID: PMC9127712 DOI: 10.1001/jamapediatrics.2022.1519] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Children and adults spend large amounts of their leisure time using screen media, which may affect their health and behavior. OBJECTIVE To investigate the effect of reducing household recreational screen media use on physical activity and sleep in children and adults. DESIGN, SETTING, AND PARTICIPANTS This was a cluster randomized clinical trial with a 2-week follow-up. Enrollment began on June 6, 2019, and ended on March 30, 2021. This study included a population-based sample from 10 Danish municipalities. A total of 89 families (181 children and 164 adults) were recruited based on a population-based survey on screen media habits in families with children. To be eligible, the responding parent had to list self-reported recreational screen use greater than the 40th percentile of recreational screen time use in the source population (>2.4 hours per day). In addition, the parent had to be full-time employed (with no regular night shifts) or enrolled in full-time education. INTERVENTIONS Families were randomly assigned to the screen media reduction intervention (45 families, 86 children, 82 adults) designed to ensure participant compliance to a maximum use of screen media (≤3 hours per week) for a 2-week period. Families randomly assigned to the control group (44 families, 95 children, 82 adults) were instructed to carry on as usual. MAIN OUTCOMES AND MEASURES The primary outcome was between-group difference in leisure nonsedentary activity (in minutes per day) measured by combined thigh and waist accelerometry. Secondary outcomes included other physical activity and sleep parameters measured by single-channel electroencephalography. RESULTS Among the 89 randomized families (intervention group [45 families]: 86 children; mean [SD] age, 8.6 [2.7] years; 44 boys [51%]; 42 girls [49%]; control group [44 families]: 95 children, mean [SD] age, 9.5 [2.5] years; 38 boys [40%]; 57 girls [60%]), 157 children (87%) had complete data on the primary outcome. Eighty-three children (97%) in the intervention group were compliant to the screen use reduction during the intervention. The mean (SD) change in leisure nonsedentary activity in the intervention group was 44.8 (63.5) minutes per day and in the control group was 1.0 (55.1) minute per day (intention-to-treat between-group mean difference, 45.8 minutes per day; 95% CI, 27.9-63.6 minutes per day; P < .001). No significant between-group mean differences were observed between intervention and control for the electroencephalography-based sleep outcomes. CONCLUSIONS AND RELEVANCE In this cluster randomized clinical trial, a recreational screen media reduction intervention resulted in a substantial increase in children's engagement in physical activity. The large effect size suggests that the high levels of recreational screen media use seen in many children should be a public health concern. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT04098913.
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Affiliation(s)
- Jesper Pedersen
- Department of Sports Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
| | - Martin Gillies Banke Rasmussen
- Department of Sports Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark,Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark
| | - Sarah Overgaard Sørensen
- Department of Sports Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
| | - Sofie Rath Mortensen
- Department of Sports Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark,Research Unit PROgrez, Department of Physiotherapy and Occupational Therapy, Naestved-Slagelse-Ringsted Hospitals, Region Zealand, Denmark
| | - Line Grønholt Olesen
- Department of Sports Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
| | - Jan Christian Brønd
- Department of Sports Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
| | - Søren Brage
- Department of Sports Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark,MRC Epidemiology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Peter Lund Kristensen
- Department of Sports Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
| | - Anders Grøntved
- Department of Sports Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark
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Sørensen SO, Pedersen J, Rasmussen MG, Kristensen PL, Grøntved A. Feasibility of home-based sampling of salivary cortisol and cortisone in healthy adults. BMC Res Notes 2021; 14:406. [PMID: 34727972 PMCID: PMC8561883 DOI: 10.1186/s13104-021-05820-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 10/26/2021] [Indexed: 11/25/2022] Open
Abstract
Objective Salivary cortisol and cortisone are used as biomarkers of physiological stress. Careful sampling of saliva for profiling of awakening response and the diurnal slope can be challenging in free-living environments, and validated sampling protocols are lacking. Therefore, we investigated (1) the level of compliance to a three-day home-based salivary sampling protocol, and (2) the within subject day-to-day variability of cortisol and cortisone outcomes and the required measuring days to obtain high reproducibility. Results Nineteen healthy adults (mean age: 42, 50% females) participated. Participants collected in total 434 salivary samples out of 456 scheduled (four samples per day over three consecutive days at two time points). We found high level of compliance to the proposed free-living salivary sampling protocol with 18 (95%) and 16 (84%) participants being compliant to numbers and timing of samples, respectively. The area under the curve for the morning salivary samples and peak-to-bed slope had moderate reproducibility for cortisol and cortisone (intraclass correlation coefficient: 0.51–0.68, and mean coefficient of variation: 14.7%-75.3%). Three-to-four measuring days were required for high reproducibility of the area under the curve for the morning salivary samples and peak-to-bed slope using this free-living salivary sampling protocol. Trial registration Clinical trial registered with www.clinicaltrials.gov (NCT03788525). Supplementary Information The online version contains supplementary material available at 10.1186/s13104-021-05820-4.
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Affiliation(s)
- Sarah Overgaard Sørensen
- Research Unit for Exercise Epidemiology, Department of Sports Science and Clinical Biomechanics, Centre of Research in Childhood Health, University of Southern Denmark, Campusvej 55, 5230, Odense, Denmark.
| | - Jesper Pedersen
- Research Unit for Exercise Epidemiology, Department of Sports Science and Clinical Biomechanics, Centre of Research in Childhood Health, University of Southern Denmark, Campusvej 55, 5230, Odense, Denmark
| | - Martin G Rasmussen
- Research Unit for Exercise Epidemiology, Department of Sports Science and Clinical Biomechanics, Centre of Research in Childhood Health, University of Southern Denmark, Campusvej 55, 5230, Odense, Denmark
| | - Peter L Kristensen
- Research Unit for Exercise Epidemiology, Department of Sports Science and Clinical Biomechanics, Centre of Research in Childhood Health, University of Southern Denmark, Campusvej 55, 5230, Odense, Denmark
| | - Anders Grøntved
- Research Unit for Exercise Epidemiology, Department of Sports Science and Clinical Biomechanics, Centre of Research in Childhood Health, University of Southern Denmark, Campusvej 55, 5230, Odense, Denmark
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Lo Leggio L, Dal Degan F, Poulsen P, Sørensen SO, Harlow K, Harris P, Larsen S. Crystallization and preliminary X-ray analysis of maltose O-acetyltransferase. Acta Crystallogr D Biol Crystallogr 2001; 57:1915-8. [PMID: 11717516 DOI: 10.1107/s0907444901016298] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2001] [Accepted: 10/02/2001] [Indexed: 11/10/2022]
Abstract
Maltose O-acetyltransferase (Mac) is a member of the hexapeptide-repeat family of enzymes, which contains proteins with left-handed parallel beta-helix architecture forming homotrimers. Diffraction data for four well diffracting crystal forms were collected. Crystal form I diffracted beyond 1.53 A resolution but was perfectly merohedrally twinned with an apparent space group P622. Crystal forms II and III (space groups R3 and C2, respectively) could be obtained under very similar conditions by adjusting the buffer pH differently. Crystal forms II and III had several monomers in the asymmetric unit and were difficult to derivatize. However, during soaking with trimethyl lead acetate, the form III crystals dissolved and crystals with a different habit and space group grew in their place (form IV). In three of the crystal forms, a ladder of peaks was visible in the native Patterson maps along the c axis. These peaks were interpreted as corresponding to the vectors between the beta-strands in the turns of the beta-helix. Crystal form IV is suitable for structure determination of Mac exploiting the anomalous scattering of lead.
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Affiliation(s)
- L Lo Leggio
- Centre for Crystallographic Studies, Chemical Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
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Davy A, Svendsen I, Sørensen SO, Blom Sørensen M, Rouster J, Meldal M, Simpson DJ, Cameron-Mills V. Substrate specificity of barley cysteine endoproteases EP-A and EP-B. Plant Physiol 1998; 117:255-261. [PMID: 9576795 PMCID: PMC35010 DOI: 10.1104/pp.117.1.255] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/1997] [Accepted: 02/04/1998] [Indexed: 05/22/2023]
Abstract
The cysteine endoproteases (EP)-A and EP-B were purified from green barley (Hordeum vulgare L.) malt, and their identity was confirmed by N-terminal amino acid sequencing. EP-B cleavage sites in recombinant type-C hordein were determined by N-terminal amino acid sequencing of the cleavage products, and were used to design internally quenched, fluorogenic peptide substrates. Tetrapeptide substrates of the general formula 2-aminobenzoyl-P2-P1-P1'-P2'-tyrosine(NO2)-aspartic acid, in which cleavage occurs between P1 and P1', showed that the cysteine EPs preferred phenylalanine, leucine, or valine at P2. Arginine was preferred to glutamine at P1, whereas proline at P2, P1, or P1' greatly reduced substrate kinetic specificity. Enzyme cleavage of C hordein was mainly determined by the primary sequence at the cleavage site, because elongation of substrates, based on the C hordein sequence, did not make them more suitable substrates. Site-directed mutagenesis of C hordein, in which serine or proline replaced leucine, destroyed primary cleavage sites. EP-A and EP-B were both more active than papain, mostly because of their much lower Km values.
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Affiliation(s)
- A Davy
- Carlsberg Research Laboratory, Department of Chemistry and Department of Physiology, Carlsberg Laboratory, Gammel Carlsbergvej 10, DK-2500 Valby, Denmark
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Bruun AW, Svendsen I, Sørensen SO, Kielland-Brandt MC, Winther JR. A high-affinity inhibitor of yeast carboxypeptidase Y is encoded by TFS1 and shows homology to a family of lipid binding proteins. Biochemistry 1998; 37:3351-7. [PMID: 9521655 DOI: 10.1021/bi971286w] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A 25-kDa inhibitor of the vacuolar enzyme carboxypeptidase Y from Saccharomyces cerevisiae has been characterized. The inhibitor, Ic, binds tightly with an apparent Ki of 0.1 nM. Consistent with a cytoplasmic localization, Ic is soluble and contains no sequences which could serve as potential signals for transport into the endoplasmic reticulum. Surprisingly, Ic is encoded by TFS1, which has previously been isolated as a high-copy suppressor of cdc25-1. CDC25 encodes the putative GTP exchange factor for Ras1p/Ras2p in yeast. In an attempt to rationalize this finding, we looked for a physiological relationship by deleting or overexpressing the gene for carboxypeptidase Y in a cdc25-1 strain. However, this did not change the phenotype of this mutant strain. Ic is the first member of a new family of protease inhibitors. The inhibitor is not hydrolyzed on binding to CPY. It has fairly high degree of specificity, showing a 200-fold higher Ki toward a carboxypeptidase from Candida albicans which is highly homologous to carboxypeptidase Y. The TFS1 gene product shows extensive similarity to a class of proteins termed "21-23-kDa lipid binding proteins", members of which are found in several higher eukaryotes, including man. These proteins are highly abundant in some tissues (e.g., brain) and have in general been found to bind lipids. Considering their homology to Ic, it is tempting to speculate that they may also be inhibitors of serine carboxypeptidases.
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Affiliation(s)
- A W Bruun
- Department of Yeast Genetics, Carlsberg Laboratory, Copenhagen Valby, Denmark
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Abstract
The accessibility of the active-site cleft of procarboxypeptidase Y from Saccharomyces cerevisiae has been studied by chemical modifications of two specific amino-acid residues. Previous studies have shown that these residues, Cys-341 and Met-398 in the mature enzyme, are located in the S1 and S'1 substrate binding sites, respectively, of carboxypeptidase Y. We have found that these residues also in proCPY are accessible to modification with fairly bulky reagents and in the case of Met-398 the rate of modification is even faster than in carboxypeptidase Y. While the catalytic serine in the mature enzyme reacts with diisopropylfluorophosphate, this is not the case for procarboxypeptidase Y.
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Affiliation(s)
- S O Sørensen
- Carlsberg Laboratory, Department of Yeast Genetics, Copenhagen Valby, Denmark
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Sørensen SO, van den Hazel HB, Kielland-Brandt MC, Winther JR. pH-dependent processing of yeast procarboxypeptidase Y by proteinase A in vivo and in vitro. Eur J Biochem 1994; 220:19-27. [PMID: 8119286 DOI: 10.1111/j.1432-1033.1994.tb18594.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Carboxypeptidase Y is a vacuolar enzyme from Saccharomyces cerevisiae. It enters the vacuole as a zymogen, procarboxypeptidase Y, which is immediately processed in a reaction involving two endoproteases, proteinase A and proteinase B. We have investigated the in vitro activation of purified procarboxypeptidase Y by purified proteinase A. This has identified two different processing intermediates; one active and one inactive. The intermediates define a 33 amino acid segment of the 91 amino acid propeptide as sufficient for maintaining the enzyme in an inactive state. The inactive intermediate was isolated from a processing reaction at neutral pH. In order to investigate the influence of vacuolar pH on processing in vivo, the autoactivation of proteinase A and its processing of procarboxypeptidase Y were studied in a vma2 prb1 mutant, which is deficient in vacuolar acidification and proteinase B activity. Efficient processing of procarboxypeptidase Y in the absence of proteinase B is dependent on acidic vacuolar pH, and the processing at neutral pH is slow and takes place in two steps similar to those identified in vitro.
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Affiliation(s)
- S O Sørensen
- Carlsberg Laboratory, Department of Yeast Genetics, Copenhagen, Valby, Denmark
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