Characterization of microbial antifreeze protein with intermediate activity suggests that a bound-water network is essential for hyperactivity

Antifreeze proteins (AFPs) inhibit ice growth by adsorbing onto specific ice planes. Microbial AFPs show diverse antifreeze activity and ice plane specificity, while sharing a common molecular scaffold. To probe the molecular mechanisms responsible for AFP activity, we here characterized the antifreeze activity and crystal structure of TisAFP7 from the snow mold fungus Typhula ishikariensis. TisAFP7 exhibited intermediate activity, with the ability to bind the basal plane, compared with a hyperactive isoform TisAFP8 and a moderately active isoform TisAFP6. Analysis of the TisAFP7 crystal structure revealed a bound-water network arranged in a zigzag pattern on the surface of the protein’s ice-binding site (IBS). While the three AFP isoforms shared the water network pattern, the network on TisAFP7 IBS was not extensive, which was likely related to its intermediate activity. Analysis of the TisAFP7 crystal structure also revealed the presence of additional water molecules that form a ring-like network surrounding the hydrophobic side chain of a crucial IBS phenylalanine, which might be responsible for the increased adsorption of AFP molecule onto the basal plane. Based on these observations, we propose that the extended water network and hydrophobic hydration at IBS together determine the TisAFP activity.

Characterization of microbial antifreeze protein with intermediate activity suggests that a bound-water network is essential for hyperactivity

Antifreeze proteins (AFPs) inhibit ice growth by adsorbing onto a specific ice plane. Microbial AFPs show diverse antifreeze activity and ice plane specificity, while sharing a common molecular scaffold. To probe the molecular mechanisms responsible for AFP activity, we here characterized the antifreeze activity and crystal structure of TisAFP7 from the snow mold fungus Typhula ishikariensis. TisAFP7 exhibited intermediate activity, with the ability to bind ice basal plane, compared with a hyperactive isoform TisAFP8 and a moderately active isoform TisAFP6. Analysis of the TisAFP7 crystal structure revealed a bound-water network arranged in a zigzag pattern on the surface of the protein’s ice-binding site (IBS). While the three AFP isoforms shared the water network pattern, the network on TisAFP7 IBS was not extensive, which was likely related to its intermediate activity. Analysis of the TisAFP7 crystal structure also revealed the presence of additional water molecules that form a ring-like network surrounding the hydrophobic side chain of a crucial IBS phenylalanine, which might be responsible for the increased adsorption of AFP molecule onto the basal plane. Based on these observations, we propose that the extended water network and hydrophobic hydration at IBS together determine the TisAFP activity.

Total Antioxidant Capacity of Thai Herbal Teas by the Ferric Reducing Antioxidant Power

The main objective aimed to compare in vitro antioxidant power of different recipes of Thai herbal teas including of Tatirot, Krajeab, Kamfoi, and Kesorn Bua. The ferric reducing/antioxidant power (FRAP) assay was used to measure the total antioxidant power of freshly brewed tea. Results showed that different Thai tea recipes had slightly different in vitro antioxidant power. The herbal teas recipe was expressed as µM of antioxidant power/g of dried Thai tea recipes. Values ranges as 555.62±0.77-908.43±0.69 µM/1g of Thai herbal tea, especially Krajeab tea showed strongly antioxidant of 908.43±0.69 µM/1g of tea when compared with other samples. Therefore, it has confirmed that the antioxidant power of Thai herbal tea recipes is considerably intermediate activity than vitamin C

Chromospheric activity catalogue of 4454 cool stars

Context.Chromospheric activity monitoring of a wide range of cool stars can provide valuable information on stellar magnetic activity and its dependence on fundamental stellar parameters such as effective temperature and rotation.Aims.We compile a chromospheric activity catalogue of 4454 cool stars from a combination of archival HARPS spectra and multiple other surveys, including the Mount Wilson data that have recently been released by the NSO. We explore the variation in chromospheric activity of cool stars along the main sequence for stars with different effective temperatures. Additionally, we also perform an activity-cycle period search and investigate its relation with rotation.Methods.The chromospheric activity index, S-index, was measured for 304 main-sequence stars from archived high-resolution HARPS spectra. Additionally, the measured and archived S-indices were converted into the chromospheric flux ratio logRHK'. The activity-cycle periods were determined using the generalised Lomb-Scargle periodogram to study the active and inactive branches on the rotation – activity-cycle period plane.Results.The global sample shows that the bimodality of chromospheric activity, known as the Vaughan-Preston gap, is not prominent, with a significant percentage of the stars at an intermediate-activity level aroundR'HK= −4.75. Independently, the cycle period search shows that stars can lie in the region intermediate between the active and inactive branch, which means that the active branch is not as clearly distinct as previously thought.Conclusions.The weakening of the Vaughan-Preston gap indicates that cool stars spin down from a higher activity level and settle at a lower activity level without a sudden break at intermediate activity. Some cycle periods are close to the solar value between the active and inactive branch, which suggests that the solar dynamo is most likely a common case of the stellar dynamo.

Flexible trial design in practice: Dropping and adding arms in STAMPEDE (MRC PR08, CRUK/06/019)—A multiarm, multistage randomized controlled trial.

27 Background: STAMPEDE ( NCT00268476 ) is a multi-centre, RCT using novel multi‐arm, multi‐stage (MAMS) methods. We describe the methodological and practical issues arising with early stopping of recruitment to some arms following an intermediate analysis and the issues in adding new research arms during the trial. Methods: The trial recruits men with locally advanced or metastatic prostate cancer starting standard long-term hormone therapy. There are 5 research and 1 control arm assessed over 3 intermediate activity stages I-III [outcome measure: failure-free survival (FFS)] and a final efficacy stage IV [outcome measure: overall survival]. At the end of each stage, research arms are formally compared to the control arm. Accrual of further patients is discontinued early for research arms not showing sufficient evidence of activity or with adverse safety considerations; accrual continues to the other arms; this interim hurdle is increasingly stringent at each stage. The addition of new research arm(s) can be actively considered when sufficiently interesting agents emerge. New research arms are compared only to contemporaneously-recruited control arm pts using the same intermediate guidelines in a time-delayed manner. Results: (1) After the second intermediate activity analysis (Mar-2011), the IDMC recommended and the Trial Steering Committee ratified discontinuation of recruitment to two research arms for lack-of-sufficient activity. Nearly 100 recruiting centres in UK and Switzerland had to promptly implement changes. Detailed advanced preparation meant that activation was swift and recruitment continued seamlessly into Activity Stage III. (2) An application to add a new research arm, abiraterone, has been agreed by funders, industry partner and ethics committee; regulatory approval awaited. Details on methodological and practical issues and implementation of these changes will be presented. Conclusions: The STAMPEDE experiences shows that recruitment to MAMS trials is achievable and that mid-flow changes to trial design are practicable and encouraged.